CN111332123A

CN111332123A - Power-on and power-off control system and control method thereof

Info

Publication number: CN111332123A
Application number: CN202010166604.9A
Authority: CN
Inventors: 陈瑞恒; 张舟; 刘颖; 吴一龙; 王博文
Original assignee: FAW Volkswagen Automotive Co Ltd
Current assignee: FAW Volkswagen Automotive Co Ltd
Priority date: 2020-03-11
Filing date: 2020-03-11
Publication date: 2020-06-26
Anticipated expiration: 2040-03-11
Also published as: CN111332123B

Abstract

The application relates to a power-on and power-off control system. The system comprises a vehicle control unit, a bidirectional DCDC converter, a capacitor and first power supply equipment, wherein the vehicle control unit is in communication connection with the bidirectional DCDC converter, and the capacitor and the first power supply equipment are respectively and electrically connected with the bidirectional DCDC converter; the vehicle control unit is used for sending a power-on and power-off instruction to the bidirectional DCDC converter; the bidirectional DCDC converter is used for boosting a first voltage output by the first power supply equipment when the power-up and power-down command is a power-up command, so that the first power supply equipment charges the capacitor, and reducing a second voltage at two ends of the capacitor when the power-up and power-down command is a power-down command, so that energy stored in the capacitor is output to the first power supply equipment. According to the power-on and power-off control system, the bidirectional DCDC converter is adopted, so that the reliability of the contactor is improved, the service life of the contactor is prolonged, the electromagnetic interference is reduced, and the problem that the electric vehicle cannot be started due to overheating of the pre-charging resistor caused by frequent high-voltage electrification is avoided.

Description

Power-on and power-off control system and control method thereof

Technology critical domain

The application relates to a charging and discharging control technology clinical domain, in particular to a power-on and power-off control system and a control method thereof.

Background

With the popularization rate of electric vehicles in the Chinese market becoming higher and higher, some outstanding problems in the use process of electric vehicles are reflected. The adhesion fault of the contactor, electromagnetic interference and the like which occur when the electric automobile is started and flameout and high-voltage power is supplied and discharged belong to the prominent problems which frequently occur.

In order to solve the problem, the conventional technical solution at present generally connects a pre-charging circuit in parallel at two ends of the main positive contactor, and the pre-charging circuit includes a pre-charging resistor and a pre-charging contactor. When high voltage is electrified, the main negative contactor and the pre-charging contactor are closed firstly, and the high-voltage battery pre-charges and boosts the direct-current bus capacitor in the high-voltage inverter through the pre-charging circuit. When the voltage of the inner side and the outer side of the contactor reaches the allowable deviation range, the contactor is closed again, and the instantaneous current generated at the closing moment of the contactor is limited within the range which can be born by the contactor. When the voltage is reduced under high voltage, the energy of the high-voltage battery with stable voltage is reduced by using the unidirectional DCDC converter to charge the 12V storage battery, so that the normal work of each controller in the running process of the electric automobile after the high-voltage electrification is finished is ensured.

Although the above conventional technical solution greatly reduces the instantaneous current during high-voltage power-on by using the pre-charging resistor, the conventional technical solution still has defects, which at least have the following defects:

1, due to the fact that the pre-charging time cannot be too long and the voltage dividing effect of the pre-charging resistor, when the main positive contactor is closed, the voltage difference between the inner side voltage and the outer side voltage of the high-voltage battery still exists by about 10%, the voltage difference of about 10% still can generate quite large instantaneous current, the reliability of the contactor can be reduced, the service life of the contactor can be influenced, and serious electromagnetic interference can be generated.

2, if power is frequently turned on and off at high voltage, the pre-charging resistor is easily overheated, so that the electric vehicle cannot be started due to the fact that power cannot be supplied at high voltage again.

Disclosure of Invention

Therefore, it is necessary to provide a power-on and power-off control system and a control method thereof, which can improve the reliability of the contactor, prolong the service life of the contactor, reduce electromagnetic interference, and solve the problem that the electric vehicle cannot be started in the conventional technical scheme.

A power-on and power-off control system comprises a vehicle control unit, a bidirectional DCDC converter and a capacitor, wherein the vehicle control unit is in communication connection with the bidirectional DCDC converter, the capacitor is electrically connected with the bidirectional DCDC converter, and the bidirectional DCDC converter is connected with a first power supply device;

the vehicle control unit is used for sending a power-on and power-off instruction to the bidirectional DCDC converter;

the bidirectional DCDC converter is used for boosting a first voltage output by the first power supply equipment when the power-up and power-down command is a power-up command, so that the first power supply equipment charges the capacitor, and reducing a second voltage at two ends of the capacitor when the power-up and power-down command is a power-down command, so that the capacitor discharges.

In one embodiment, the system further includes a battery module, where the battery module includes a battery management system, a second power device, a first voltage sensor, a second voltage sensor, and a contactor connected to the second power device, the battery management system is communicatively connected to the vehicle control unit, and the battery module is electrically connected to the capacitor;

the first voltage sensor is used for measuring a third voltage of the second power supply device, and the second voltage sensor is used for measuring a second voltage at two ends of the capacitor;

the battery management system is used for acquiring the second voltage and the third voltage, closing the contactor when the second voltage is equal to the third voltage, and sending first notification information of closing the contactor to the vehicle control unit;

the vehicle control unit is further configured to send a command to stop boosting the first voltage to the bidirectional DCDC converter when receiving the first notification message, so that the first power supply device stops charging the capacitor.

In one embodiment, the battery management system is further configured to receive a power-off command sent by the vehicle control unit, open the contactor, and send a second notification that the contactor is opened to the vehicle control unit.

In one embodiment, the contactor includes a positive contactor connected to the positive pole of the second power device and a negative contactor connected to the negative pole of the second power device.

In one embodiment, the system further comprises the first power supply device;

the first power supply device is used for receiving and storing energy released by the capacitor after the bidirectional DCDC converter reduces the second voltage at two ends of the capacitor;

in one embodiment, the first power supply device is a storage battery.

In one embodiment, the capacitor is a voltage stabilizing capacitor built in the high voltage inverter.

A power-up and power-down control method, the method comprising:

the vehicle control unit sends a power-on and power-off instruction to the bidirectional DCDC converter;

when the power-on and power-off command is a power-on command, a bidirectional DCDC converter in communication connection with the vehicle control unit boosts a first voltage output by first power supply equipment, so that the first power supply equipment charges the capacitor, and the first power supply equipment and the capacitor are respectively and electrically connected with the bidirectional DCDC converter;

and when the power-up and power-down command is a power-down command, the bidirectional DCDC converter reduces the second voltage at two ends of the capacitor, so that the capacitor is discharged.

In one embodiment, the method further includes:

a first voltage sensor in the battery module measures a third voltage of a second power supply device in the battery module in real time, a second voltage sensor in the battery module measures a second voltage at two ends of the capacitor in real time, and the battery module is electrically connected with the capacitor;

a battery management system in the battery module collects the second voltage and the third voltage, closes a contactor connected with the second power supply device when the second voltage is equal to the third voltage, and sends first notification information of closing the contactor to the vehicle controller, wherein the battery management system is in communication connection with the vehicle controller;

and the vehicle control unit receives the first notification information and sends a command of stopping boosting the first voltage to the bidirectional DCDC converter, so that the first power supply equipment stops charging the capacitor.

In one embodiment, the method further includes:

the battery management system receives a power-off command sent by the vehicle control unit, disconnects the contactor and sends second notification information of the disconnection of the contactor to the vehicle control unit.

In one embodiment, the method further includes:

and after the bidirectional DCDC converter reduces the second voltage at the two ends of the capacitor, the energy released by the capacitor is stored in the first power supply equipment.

The power-on and power-off control system comprises a vehicle control unit, a bidirectional DCDC converter, a capacitor and first power supply equipment, wherein the vehicle control unit is in communication connection with the bidirectional DCDC converter, and the capacitor and the first power supply equipment are respectively and electrically connected with the bidirectional DCDC converter; the vehicle control unit is used for sending a power-on and power-off instruction to the bidirectional DCDC converter; the bidirectional DCDC converter is used for boosting a first voltage output by the first power supply equipment when the power-up and power-down command is a power-up command, so that the first power supply equipment charges the capacitor, and reducing a second voltage at two ends of the capacitor when the power-up and power-down command is a power-down command, so that energy stored in the capacitor is output to the first power supply equipment. According to the power-on and power-off control system, a pre-charging circuit is omitted, the problems that the reliability of a contactor is reduced, the service life of the contactor is influenced and serious electromagnetic interference is generated due to the fact that the pre-charging circuit is adopted in the traditional technology are solved, and meanwhile, the problem that in the traditional technical scheme, due to the fact that the pre-charging resistor is overheated due to frequent high-voltage power-on, the high-voltage power-on cannot be carried out again, and the electric vehicle cannot be started is solved.

Drawings

FIG. 1 is a circuit schematic of a power up and power down control system provided in an exemplary embodiment of the present application;

fig. 2 is a schematic circuit diagram of a power-on and power-off control system provided in a conventional technical solution;

fig. 3 is a flowchart illustrating a power-on and power-off control method provided in an exemplary embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

In one embodiment, as shown in fig. 1, a schematic circuit diagram of a power-on and power-off control system is provided, and as shown in fig. 1, the system includes a vehicle control unit 11, i.e., the VCU in fig. 1, a bidirectional DCDC converter 12, and a capacitor cstr, where the vehicle control unit 11 is communicatively connected to the bidirectional DCDC converter 12, the capacitor cstr is electrically connected to the bidirectional DCDC converter 12, and the bidirectional DCDC converter 12 is connected to a first power supply device 13;

the vehicle control unit 11 is configured to send a power-up and power-down instruction to the bidirectional DCDC converter 12;

the bidirectional DCDC converter 12 is configured to boost a first voltage output by the first power supply device 13 when the power-up/power-down instruction is a power-up instruction, so that the first power supply device 13 charges the capacitor C stably, and reduce a second voltage at two ends of the capacitor C stably when the power-up/power-down instruction is a power-down instruction, that is, a dc bus voltage in fig. 1, so that the capacitor C stably discharges.

Specifically, the vehicle control unit is used for realizing the cooperative work between the bidirectional DCDC converter 12 and the capacitor cstability. The bidirectional DCDC converter 12 may step down the high voltage of the battery system to a low voltage to charge the power supply of the first power supply device 13, or may step up the low voltage output from the first power supply device 13 to a high voltage to supplement the high voltage power demand.

When the vehicle control unit 11 is powered on at a high voltage, that is, when the capacitor C is charged stably, the vehicle control unit sends a power-on command to the bidirectional DCDC converter 12, and the bidirectional DCDC converter 12 is required to boost the first voltage output by the first power supply device 13, so as to charge the capacitor C stably. The scheme saves a pre-charging circuit in the traditional technical scheme, solves the problems of reliability reduction of a contactor and serious electromagnetic interference caused by the utilization of the pre-charging circuit in the traditional technology, and solves the problems that the pre-charging resistor is overheated easily caused in the traditional technology, so that the electric vehicle cannot be powered on at high voltage again, cannot be started for use and the like.

When the capacitor is discharged under high voltage, the bidirectional DCDC converter 12 is started to reduce the voltage of the energy stored in the capacitor cstability for discharging.

In one embodiment, the above-mentioned system further includes a battery module 15, the battery module 15 includes a battery management system 151, i.e., BMS in fig. 1, a second power device 152, a first voltage sensor 153, a second voltage sensor 154, and contactors connected to the second power device 152, i.e., a contactor K positive and a contactor K negative in fig. 1, the battery management system 151 is communicatively connected to the vehicle controller 11, and the battery module 15 is electrically connected to the capacitor C.

The first voltage sensor 153 is used for measuring a third voltage of the second power supply device 152, i.e. the battery voltage in fig. 1, and the second voltage sensor 154 is used for measuring a second voltage across the capacitor cstr, i.e. the dc bus voltage in fig. 1;

the battery management system 151 is configured to collect the second voltage and the third voltage, close the contactor K positive and the contactor K negative when the second voltage is equal to the third voltage, and send first notification information that the contactor K positive and the contactor K negative are closed to the vehicle control unit 11;

the vehicle control unit 11 is further configured to send, after receiving the first notification message, an instruction to stop boosting the first voltage to the bidirectional DCDC converter 12, so that the first power supply device 13 stops stably charging the capacitor C.

Specifically, the battery management system 151 may collect and feed back a third voltage of the first voltage sensor 153 and a second voltage of the second voltage sensor 154, send the collected second voltage and the collected third voltage to the vehicle control unit 11, and execute opening or closing of the positive contactor K and the negative contactor K in response to a power-on/power-off command of the vehicle control unit 11. In one embodiment, the battery module 15 may be a high voltage battery.

In one embodiment, the power-on and power-off control method provided by the application can be applied to high-voltage power-on and power-off of an electric automobile. Specifically, when the high voltage is powered on, that is, the capacitor is charged stably, the process may be as follows:

the vehicle control unit 11 receives a starting instruction of a user and initiates a charging request;

the bidirectional DCDC converter 12 receives the charging request, boosts the output voltage of the first power supply device 13, gradually increases the dc bus voltage V2, and precharges the capacitor C until the boost V2 reaches the third voltage V1;

the battery management system 151 detects the third voltage V1 and the second voltage V2 in real time, closes the contactor K positive first and then closes the contactor K negative when the third voltage V1 and the second voltage V2 are consistent, and feeds back first notification information that the contactor K positive and the contactor K negative are in a closed state to the VCU.

After receiving the first notification message, the vehicle control unit 11 sends a command to the bidirectional DCDC converter 12 to stop boosting the voltage of the 12V battery 13 to the capacitor C for stable pre-charging, and high-voltage power-on is completed.

This technical scheme utilizes two-way DCDC converter to give the steady pre-charge of electric capacity C with 12V battery voltage steps up, can realize closing the contactor under the condition that direct current bus voltage V2 equals battery voltage V1 for there is not the voltage difference after closing the contactor, just can not produce instantaneous current impact yet.

Referring to fig. 2, fig. 2 is a schematic circuit diagram of a charging and discharging control circuit adopted by an electric vehicle in a conventional technical solution according to an embodiment. As shown in fig. 2, in the conventional technical solution, a schematic circuit diagram of charge and discharge control includes a vehicle control unit 21, a unidirectional DCDC converter 22, a high-voltage inverter 23, a 12V battery 24, and a battery module 25. The high voltage inverter 23 includes a capacitor cstability, a switch K, and a resistor R. The high voltage battery module 25 includes a cell 251, a first voltage sensor 252, a BMS battery management system 253, a second sensor 254, and main positive and negative contactors K-positive and K-negative and a pre-charge circuit 255, and the pre-charge circuit 255 includes a pre-charge contactor K-pre and a pre-charge resistor R-pre.

Specifically, the battery management system 253 is configured to collect and feed back signals of a battery voltage V1 at the inner side of the high-voltage battery contactor and a dc bus voltage V2 at the outer side of the contactor, and control the pre-closing and pre-opening actions of the main positive contactor K, the main negative contactor K, and the pre-charging contactor K. The high-voltage inverter 23 is used for converting direct current of the high-voltage battery into alternating current to drive the motor, and a capacitor Ci is arranged at the direct current end of the high-voltage inverter 23 to ensure stable supply of direct current end voltage. The unidirectional DCDC converter 22 is used to step down the high voltage battery to charge the vehicle 12V battery 24. The vehicle control unit 21 is configured to implement cooperative operation of the battery module 25, the unidirectional DCDC converter 22, and the high-voltage inverter 23.

Because the capacitor C in the high-voltage inverter 23 exists stably, if the main positive contactor K and the main negative contactor K in the high-voltage battery are directly closed, a loop formed between the battery module 25 and the capacitor C is instantaneously short-circuited, so that a great instantaneous current is generated, the service life of the contactor is seriously shortened, and even the contactor is damaged. In order to reduce the instantaneous current when the contactor is closed, the inside battery voltage V1 and the outside dc bus voltage V2 of the contactor need to be kept within the allowable deviation range to allow the contactor to be closed. Therefore, a pre-charging circuit is added to the positive ends of the main positive contactor K of the high-voltage battery module 25 to ensure that the voltage V1 of the battery inside the contactor and the voltage V2 of the dc bus outside the contactor are kept within the allowable deviation range as much as possible. When receiving a high-voltage power-on command of the vehicle control unit 21, the battery management system 253 closes the main negative contactor K negative and the pre-charging contactor K pre-and pre-limits the current for stably charging the capacitor C through the pre-charging resistor R. And when the direct-current bus voltage V2 reaches about 90% of the battery voltage V1, closing the main positive contactor K, disconnecting the pre-charging contactor K of the pre-charging contactor, and completing the high-voltage electrification after the pre-charging.

However, due to the voltage dividing function of the pre-charging resistor 2661 and the fact that the pre-charging time cannot be too long, the voltage difference (V1-V2) between the two ends still reaches about 10% V1 when the main positive contactor K is closed, the internal resistance of the high-voltage battery is very small, and a circuit formed by the high-voltage battery and the capacitor C is subjected to transient short circuit when the main positive contactor K is closed, so that a considerable transient current surge is generated, the electromagnetic interference problem is generated, and the service life of the contactor is also reduced.

Therefore, the bidirectional DCDC converter is adopted to replace the unidirectional DCDC converter, a pre-charging circuit is omitted, and the problems that in the traditional technical scheme, the capacitor is pre-charged by the high-voltage battery by utilizing the pre-charging resistor and the pre-charging contactor, and when the contactor is closed, the voltage difference between the inner side and the outer side of the contactor reaches about 10% V1 and instantaneous current impact can be generated due to the fact that the voltage division effect of the pre-charging resistor and the pre-charging time cannot be too long are solved.

According to the high-voltage power-on method based on the bidirectional DCDC converter, instantaneous current impact cannot be generated when the contactor is closed, the reliability of the contactor is greatly improved, and the problem of electromagnetic interference generated by the action of the contactor is effectively solved. Meanwhile, the situation that the electric automobile cannot be started for use due to the overheating problem of the pre-charging resistor after high-voltage electrification is frequently avoided.

In one embodiment, the battery management system 151 is further configured to receive a power-off command sent by the vehicle control unit 11, open the contactor, and send a second notification message that the contactor is completely opened to the vehicle control unit 11.

In one embodiment, the contactor includes a main positive contactor K positive connected to the main positive electrode of the second power device 152, and a main negative contactor K negative connected to the negative electrode of the second power device 152.

In one embodiment, the above system may further include the first power supply device 13;

the first power supply device 13 is configured to receive and store energy released by the capacitor cstability after the bidirectional DCDC converter 12 steps down the second voltage across the capacitor cstability.

In one embodiment, the first power supply device 13 may be a battery.

Specifically, the first power supply device 13 is configured to provide electric energy to charge the capacitor cstably during a charging phase, and receive electric energy released by the capacitor cstably during a discharging phase to store energy, so as to avoid energy waste.

Further, when the capacitor C is powered off at a high voltage, that is, stably discharged, the process may be as follows:

the vehicle control unit 11 receives a closing instruction of a user, initiates a high-voltage reduction command, disconnects the positive main contactor K from the positive battery management system 165, disconnects the negative main contactor K from the negative battery management system 165, and informs the vehicle control unit 11;

after receiving the notification information, the vehicle control unit 11 sends a discharge request to the bidirectional DCDC converter 12, starts the bidirectional DCDC converter 12 to step down the energy stored in the capacitor cactus to charge the 12V storage battery 13, and converts and stores the energy stored in the capacitor cactus into the 12V storage battery 13 to realize energy recovery.

The bidirectional DCDC converter is adopted, has high control precision and good dynamic response, and can reduce the voltage of constantly changing energy in the stability of the capacitor C to charge a 12V storage battery, thereby realizing the recovery of the energy in the stability of the capacitor C.

Referring to fig. 2, in the conventional technical solution, a unidirectional DCDC converter is adopted, and due to low control accuracy and poor dynamic response, the unidirectional DCDC converter cannot step down the energy with constantly changing voltage in the capacitor to charge the 12V battery, and cannot recover the energy. The energy in the capacitor can be converted into heat energy to be quickly consumed by closing the discharge relay K and the resistor R, so that energy waste is caused.

In one embodiment, the capacitor C is a voltage stabilizing capacitor built in the high voltage inverter 14. The system described above includes the high voltage inverter 14 described above. The high voltage inverter 14 is used for converting the direct current of the high voltage battery into alternating current to drive the motor, and the capacitor C is stably arranged at the direct current end of the high voltage inverter 14 to ensure the stability of the direct current end voltage.

In an embodiment, referring to fig. 3, fig. 3 provides a flowchart of a power-on and power-off control method, as shown in fig. 3, the power-on and power-off control method includes:

and S31, the vehicle control unit sends a power-on and power-off command to the bidirectional DCDC converter.

And S32, when the power-up and power-down command is a power-up command, the bidirectional DCDC converter in communication connection with the vehicle control unit boosts a first voltage output by a first power supply device, so that the first power supply device charges the capacitor, and the first power supply device and the capacitor are respectively and electrically connected with the bidirectional DCDC converter.

And S33, when the power-up and power-down command is a power-down command, the bidirectional DCDC converter reduces the second voltage at two ends of the capacitor, so that the capacitor is discharged.

In one embodiment, the vehicle control unit is communicatively connected to the bidirectional DCDC converter. The capacitor cstr and the first power supply device 13 are electrically connected to the bidirectional DCDC converter 12, respectively.

Specifically, the vehicle control unit sends a power-up and power-down instruction to the bidirectional DCDC converter, and the bidirectional DCDC converter adjusts the voltage at two ends of the capacitor or the voltage at two ends of the first voltage device according to the power-up and power-down instruction, so that the capacitor is charged or discharged.

In one embodiment, the method may further include:

In an embodiment, the battery module includes a battery management system, a second power device, a first voltage sensor, a second voltage sensor, a main positive contactor connected to a positive electrode of the second power device, and a main negative contactor connected to a negative electrode of the second power device, the battery management system 151 is in communication connection with the vehicle control unit 11, and the battery module is electrically connected to the capacitor.

When the vehicle is powered on at high voltage, the vehicle control unit initiates a charging request, and the bidirectional DCDC converter boosts the output voltage of the first power supply device, so that the boosted voltage charges the capacitor.

Further, the battery management system collects a third voltage V1 and a second voltage V2 in real time, when V1 is detected to be V2, the main negative contactor is closed first, then the main positive contactor is closed, and first notification information that the main negative contactor and the main positive contactor are in a closed state is fed back to the vehicle control unit;

further, the vehicle control unit sends a command of stopping boosting the voltage of the 12V storage battery 13 to the bidirectional DCDC converter 12 to pre-charge the capacitor C, and the high-voltage power-on is completed.

In one embodiment, the method may further include:

In one embodiment, when the vehicle controller is powered off at a high voltage, namely, when the capacitor is discharged, the vehicle controller receives a turn-off command of a user, initiates a high-voltage turn-off command, and the battery management system disconnects the main positive contactor and the main negative contactor and informs the vehicle controller;

and after receiving the notification information, the vehicle control unit sends a discharging request to the bidirectional DCDC converter, starts the bidirectional DCDC converter to reduce the voltage of the energy stored in the capacitor and charge the 12V storage battery, converts and stores the energy stored in the capacitor into the 12V storage battery, and realizes energy recovery.

In summary, the bidirectional DCDC converter is adopted to replace the original unidirectional DCDC converter, so that the following beneficial effects can be brought:

firstly, because the bidirectional DCDC converter can boost the voltage of the 12V storage battery to the voltage stabilizing capacitor C for stable pre-charging, the bidirectional DCDC converter can replace a pre-charging circuit to realize the charging of the voltage stabilizing capacitor. In addition, after the direct-current bus voltage V2 on the outer side of the contactor is equal to the high-voltage battery voltage V1 on the inner side of the contactor, the main positive contactor K positive and the main negative contactor K negative are closed, and at the moment, no voltage difference exists between the inner side and the outer side before contact, and instantaneous current impact cannot be generated. And a certain voltage difference still exists by adopting the pre-charging circuit, and certain instantaneous current impact can be generated. Therefore, the bidirectional DCDC converter can solve the problems of the traditional technology that the reliability of the contactor is reduced and the electromagnetic interference is serious due to the generation of instant current impact.

Secondly, by using the pre-charging circuit, if the power is frequently charged up and down at high voltage, the pre-charging resistor is easily overheated, so that the problem that the electric vehicle cannot be started for use due to the fact that the power cannot be charged at high voltage again is caused. However, with a bidirectional DCDC converter, this problem can be solved since the precharge circuit can be omitted.

Thirdly, because the bidirectional DCDC converter can boost the voltage of the 12V storage battery to the voltage stabilizing capacitor C for stable pre-charging, a pre-charging circuit can be omitted, and the cost is saved.

Fourthly, the bidirectional DCDC converter can also realize voltage reduction of high-voltage in a voltage stabilizing capacitor C to charge the 12V power supply. Energy recovery can be achieved using this principle. In the traditional scheme, the energy stored in the voltage stabilizing capacitor C can only be converted into heat energy to be quickly consumed in the power-off stage by adopting the unidirectional DCDC converter, so that energy waste is caused.

Therefore, by adopting the bidirectional DCDC converter, a pre-charging circuit can be omitted, the cost is saved, the effect better than that of the pre-charging circuit can be brought, namely instant current impact cannot be generated, the reliability of the contactor cannot be correspondingly reduced, the problem of serious electromagnetic interference is brought, and meanwhile, the energy recovery can be realized.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above examples only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the protection scope of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The power-on and power-off control system is characterized by comprising a vehicle control unit, a bidirectional DCDC converter and a capacitor, wherein the vehicle control unit is in communication connection with the bidirectional DCDC converter, the capacitor is electrically connected with the bidirectional DCDC converter, and the bidirectional DCDC converter is connected with a first power supply device;

2. The system of claim 1, further comprising a battery module including a battery management system, a second power device, a first voltage sensor, a second voltage sensor, and a contactor coupled to the second power device, the battery management system communicatively coupled to the vehicle control unit, the battery module electrically coupled to the capacitor;

3. The system of claim 2, wherein the battery management system is further configured to receive a power-down command sent by the vehicle control unit, open the contactor, and send a second notification to the vehicle control unit that the contactor is open.

4. The system of claim 2, wherein the contactor comprises a positive contactor connected to a positive pole of the second power supply device and a negative contactor connected to a negative pole of the second power supply device.

5. The system of claim 1, further comprising the first power supply device;

preferably, the first power supply device is a battery.

6. The system of claim 1, wherein the capacitor is a voltage stabilization capacitor built into the high voltage inverter.

7. A power-up and power-down control method, the method comprising:

8. The method of claim 7, further comprising:

9. The method of claim 8, further comprising:

10. The method of claim 7, further comprising: