CN113733916B

CN113733916B - High-voltage power-on method and electric automobile

Info

Publication number: CN113733916B
Application number: CN202111221340.3A
Authority: CN
Inventors: 刘光生; 王杭挺; 刘安龙
Original assignee: Guangzhou Xiaopeng Motors Technology Co Ltd
Current assignee: Guangzhou Xiaopeng Motors Technology Co Ltd
Priority date: 2021-10-20
Filing date: 2021-10-20
Publication date: 2023-10-31
Anticipated expiration: 2041-10-20
Also published as: CN113733916A

Abstract

The invention provides a high-voltage power-on method and an electric automobile, and relates to the technical field of electric automobiles, wherein the method comprises the following steps: after the open circuit of the pre-charging relay or the open circuit of the main negative relay is determined for the first time, the pre-charging relay is tried to be closed for a plurality of times or the main negative relay is tried to be closed for a plurality of times, and after the pre-charging is determined to be successful and the external circuit of the power battery is identified to be not short-circuited, whether the main positive relay is open-circuited for the first time is diagnosed; after the primary positive relay is determined to be open, a part of high-voltage power-on flow is tried to be executed for many times, and after the primary positive relay is determined to be not open, a signal that the high-voltage power-on flow is finished is sent to the whole vehicle controller. The high-voltage power-on method effectively solves the problem that the whole vehicle cannot be powered on due to the fact that the relay is electrified and the relay is not operated, and greatly improves the experience of users. The risk of short circuit of the external circuit of the power battery is effectively intercepted, so that the safety of the whole vehicle and the human body is improved. The high-voltage power-on method has higher practicability.

Description

High-voltage power-on method and electric automobile

Technical Field

The invention relates to the technical field of electric vehicles, in particular to a high-voltage boosting method and an electric vehicle.

Background

In order to improve the endurance of the existing electric automobile, the capacity and the voltage level of a power battery are higher and higher, and high-voltage safety becomes an important concern in the field of electric automobiles. In addition, in order to improve the experience of the user, the time required for the whole flow of high-voltage power-on is required to be shorter. At present, various high-voltage power-on methods exist, so that the high-voltage safety of the electric automobile is ensured, and the time for high-voltage power-on is shortened as much as possible.

Because the existing relay products have consistency differences, the relay coil is electrified and does not act at all, so that the whole vehicle cannot be electrified and has a fault, the fault cannot be electrified and needs maintenance of the trailer, and a very poor experience is brought to a user. In addition, the current high-voltage power-on method cannot well intercept the risk of short circuit (namely load short circuit) of the external circuit of the power battery, if the external circuit of the power battery is short-circuited, the risk of thermal runaway of the short circuit of the power battery can be caused by closing the main relay, and the fire burning of the power battery can be caused when serious, so that the safety of the whole vehicle and people is endangered. Therefore, it is needed to provide a high-voltage power-on method capable of solving the problem that the relay coupling coil is powered up and effectively intercepting the risk of short circuit of the external circuit of the power battery.

Disclosure of Invention

In view of the above, the present invention has been made to provide a high-voltage power-on method and an electric vehicle that overcome or at least partially solve the above problems.

In a first aspect, there is provided a method of high voltage power up, the method comprising:

after the open circuit of the pre-charging relay or the open circuit of the main negative relay is determined for the first time, the pre-charging relay is tried to be closed for a plurality of times or the main negative relay is tried to be closed for a plurality of times, wherein, the open circuit diagnosis of the pre-charging relay is carried out according to a preset strategy during the period of the repeated attempt to be closed for the pre-charging relay, and the open circuit diagnosis of the main negative relay is carried out according to the preset strategy during the period of the repeated attempt to be closed for the main negative relay;

after the fact that the pre-charging relay and the main negative relay are both closed is determined for the first time, whether pre-charging is successful or not is diagnosed according to preset logic conditions, and whether an external circuit of the power battery is short-circuited is identified;

determining that the pre-charging is successful, identifying that the external circuit of the power battery is not short-circuited, and diagnosing whether the primary main positive relay is open-circuited or not;

after the open circuit of the main positive relay is determined for the first time, a part of high-voltage power-on flow is tried to be executed for many times, wherein after each attempt is executed for the part of high-voltage power-on flow, whether the main positive relay is open circuit is diagnosed, and the part of high-voltage power-on flow is as follows: in all high-voltage power-on processes, part of the preamble processes refer to: performing a flow before a flow of diagnosing whether the main positive relay is open or not;

And after the main positive relay is determined to be not opened, sending a signal that the high-voltage power-on process is finished to the whole vehicle controller.

Optionally, performing the diagnosis of whether the main positive relay is open, includes:

executing a bus capacitor active discharging process;

detecting the change condition of the voltage of the bus capacitor terminal after the bus capacitor actively discharges;

and when the change condition meets a preset condition, determining that the main positive relay is open.

Optionally, after determining that the pre-charging relay is open or the main negative relay is open for the first time, attempting to close the pre-charging relay or attempting to close the main negative relay multiple times, wherein during the multiple attempts to close the pre-charging relay, performing a diagnosis of whether the pre-charging relay is open or not according to a preset strategy, and during the multiple attempts to close the main negative relay, performing a diagnosis of whether the main negative relay is open or not according to the preset strategy, including:

after the open circuit of the pre-charging relay is determined for the first time, diagnosing whether the pre-charging relay is open circuit or not after each attempt to close the pre-charging relay is performed; or,

after the open circuit of the pre-charging relay is determined for the first time, continuously attempting to close the pre-charging relay for preset times, and then diagnosing whether the pre-charging relay is open circuit or not;

After the fact that the pre-charging relay is not opened and the main negative relay is not adhered is determined for the first time, the main negative relay is closed for the first time, and whether the main negative relay is opened or not is diagnosed for the first time; or,

and after the primary negative relay is determined to be open for the first time, continuously attempting to close the primary negative relay for a preset number of times, and then diagnosing whether the primary negative relay is open.

after the primary negative relay is determined to be open for the first time, diagnosing whether the primary negative relay is open or not after each attempt to close the primary negative relay is carried out; or,

after the primary negative relay is determined to be open for the first time, continuously attempting to close the primary negative relay for preset times, and then diagnosing whether the primary negative relay is open;

After the main negative relay is determined to be not open-circuited and the main positive relay is not adhered, closing the pre-charging relay for the first time, and diagnosing whether the pre-charging relay is open-circuited for the first time;

after determining that the pre-charging relay is open for the first time, diagnosing whether the pre-charging relay is open or not after each attempt to close the pre-charging relay; or,

and after the open circuit of the pre-charging relay is determined for the first time, continuously attempting to close the pre-charging relay for a preset number of times, and then diagnosing whether the pre-charging relay is open circuit.

Optionally, after determining that both the pre-charging relay and the main negative relay are closed for the first time, identifying whether the external circuit of the power battery is short-circuited according to a preset logic condition includes:

detecting whether a current with a stable current value exists in the pre-charging loop or not;

detecting whether a second voltage between a second end of the main positive relay and a first end of the main negative relay is far smaller than a first voltage between the first end of the main positive relay and the first end of the main negative relay; or,

detecting whether the second voltage is near zero volts;

identifying that the power battery external circuit is short-circuited when a current with a stable current value exists in the pre-charging loop and the second voltage is far smaller than the first voltage, or when a current with a stable current value exists in the pre-charging loop and the second voltage is close to zero volt, otherwise, identifying that the power battery external circuit is not short-circuited;

The second end of the main positive relay is one end connected with the load end, the first end of the main positive relay is one end connected with the positive electrode of the power battery, and the first end of the main negative relay is one end connected with the negative electrode of the power battery.

Optionally, after determining that both the pre-charging relay and the main negative relay are closed for the first time, performing a diagnosis of whether the pre-charging is successful according to a preset logic condition, including:

detecting whether current with exponentially reduced current value exists in the pre-charging loop or not;

detecting whether the second voltage is equal to the first voltage;

and under the condition that the current value of the pre-charging loop is exponentially reduced or the second voltage is equal to the first voltage, determining that the pre-charging is successful, otherwise, determining that the pre-charging is failed.

Optionally, executing the bus capacitor active bleed flow includes:

sending a discharge instruction to a motor controller, so that the motor controller controls the upper bridge arm and the lower bridge arm to be conducted according to the discharge instruction, and then energy of a bus capacitor is discharged through a first discharge loop, wherein the first discharge loop is as follows: and a discharge loop formed by passing through the upper bridge arm from one end of the bus capacitor, passing through the motor winding, and returning to the other end of the bus capacitor through the lower bridge arm.

Optionally, executing the bus capacitor active bleed flow includes:

the first bleeder switch is controlled to be conducted so that energy of the bus capacitor is discharged through a second bleeder circuit, and the second bleeder circuit refers to: a discharging loop formed by returning one end of the bus capacitor to the other end of the bus capacitor through the first discharging switch and the pre-charging resistor; or,

and controlling the second bleeder switch to be conducted so as to enable the energy of the bus capacitor to be discharged through a third bleeder circuit, wherein the third bleeder circuit refers to: and a bleeder circuit formed by returning one end of the bus capacitor to the other end of the bus capacitor through the second bleeder switch and the bleeder resistor.

Optionally, after determining that the pre-charging is successful and identifying that the external circuit of the power battery is not shorted, performing a first diagnosis of whether the main positive relay is open, including:

after the success of pre-charging is determined and the fact that the external circuit of the power battery is not short-circuited is identified, the main positive relay is closed for the first time;

and after the primary positive relay is closed for the first time, the pre-charging relay is opened, and whether the primary positive relay is open-circuited or not is diagnosed.

Optionally, after determining that the main positive relay is open for the first time, attempting to perform a partial high voltage power-on procedure multiple times includes:

Reclosing the pre-charge relay after the primary positive relay is determined to be open for the first time;

after the pre-charging relay is closed again, according to preset logic conditions, whether pre-charging is successful or not is diagnosed, and whether an external circuit of the power battery is short-circuited is identified;

after the success of pre-charging is determined and the fact that the external circuit of the power battery is not short-circuited is identified, the main positive relay is closed for the second time;

after the main positive relay is closed for the second time, the pre-charging relay is opened again, and whether the main positive relay is open-circuited for the second time is diagnosed;

after the primary positive relay is determined to be open for the second time, the following steps are executed: reclosing the precharge relay; or alternatively

After the primary positive relay is determined to be open for the first time, the primary negative relay is disconnected;

reclosing the pre-charging relay after determining that the pre-charging relay and the main negative relay are not adhered;

after the pre-charging relay is closed again, the main negative relay is closed again;

after the main negative relay is closed again, whether the pre-charging is successful or not is diagnosed and whether an external circuit of the power battery is short-circuited is identified according to preset logic conditions; then, diagnosing whether the pre-charging is successful or not again;

after the primary positive relay is determined to be open for the second time, the following steps are executed: and opening the main negative relay.

after determining that the pre-charging relay and the main negative relay are not adhered, closing the main negative relay again;

after the main negative relay is closed again, the pre-charging relay is closed again;

after the pre-charging relay is closed again, whether pre-charging is successful or not is diagnosed according to preset logic conditions, and whether an external circuit of the power battery is short-circuited is identified;

Optionally, according to a preset logic condition, performing a diagnosis of whether the pre-charging is successful or not, and identifying whether the external circuit of the power battery is short-circuited, including:

identifying that the external circuit of the power battery is short-circuited, if the pre-charging fails, disconnecting the pre-charging relay and the main negative relay, and sending a first alarm signal to the whole vehicle controller;

and identifying that the external circuit of the power battery is not short-circuited, determining that the pre-charging fails, disconnecting the pre-charging relay and the main negative relay, and sending a second alarm signal to the whole vehicle controller.

In a second aspect, there is provided an apparatus for high voltage power up, the apparatus comprising:

the multi-time trial closing module is used for repeatedly trying to close the pre-charging relay or repeatedly trying to close the main negative relay after the pre-charging relay or the main negative relay is determined to be open for the first time, wherein whether the pre-charging relay is open or not is diagnosed according to a preset strategy during the repeated trial of closing the pre-charging relay, and whether the main negative relay is open or not is diagnosed according to the preset strategy during the repeated trial of closing the main negative relay;

The diagnosis and identification module is used for carrying out successful diagnosis on the pre-charge according to preset logic conditions after the pre-charge relay and the main negative relay are determined to be closed for the first time, and identifying whether an external circuit of the power battery is short-circuited;

the main positive relay open circuit diagnosis module is used for determining that the pre-charging is successful and identifying that the external circuit of the power battery is not short-circuited, and diagnosing whether the main positive relay is open circuit for the first time;

the execution flow module is used for repeatedly attempting to execute part of high-voltage power-on flows after the primary positive relay is determined to be open for the first time;

the main positive relay open circuit diagnosis module is further configured to perform a diagnosis of whether the main positive relay is open circuit after each attempt to execute the partial high-voltage power-on procedure, where the partial high-voltage power-on procedure is as follows: in all high-voltage power-on processes, part of the preamble processes refer to: performing a flow before a flow of diagnosing whether the main positive relay is open or not;

and the signal sending module is used for sending a signal of finishing the high-voltage power-on process to the whole vehicle controller after the main positive relay is determined not to be opened.

Optionally, the main positive relay open circuit diagnosis module includes:

The execution submodule is used for executing the bus capacitor active discharging flow;

the detection submodule is used for detecting the change condition of the voltage of the bus capacitor terminal after the bus capacitor actively discharges;

and the determining submodule is used for determining that the main positive relay is open when the change condition meets a preset condition.

Optionally, the multi-attempt closure module is specifically configured to:

after the open circuit of the pre-charging relay is determined for the first time, the pre-charging relay is tried to be closed for a plurality of times; or,

Optionally, the multi-attempt closure module is specifically configured to:

Optionally, the diagnosis and identification module is specifically configured to:

detecting whether the second voltage is near zero volts;

the method comprises the steps that when a current with a stable current value exists in the pre-charging loop and the second voltage is far smaller than the first voltage, or when a current with a stable current value exists in the pre-charging loop and the second voltage is close to zero volt, the short circuit of the power battery external circuit is identified, otherwise, the short circuit of the power battery external circuit is identified;

detecting whether the second voltage is equal to the first voltage;

Optionally, the execution submodule is specifically configured to:

Optionally, the execution submodule is configured to:

Optionally, a main positive relay closing module is used for closing the main positive relay for the first time after determining that the pre-charging is successful and identifying that the external circuit of the power battery is not short-circuited;

and the main positive relay open circuit diagnosis module is also used for opening the pre-charging relay after the main positive relay is closed for the first time so as to diagnose whether the main positive relay is open circuit for the first time.

Optionally, the execution flow module is specifically configured to:

after the primary positive relay is determined to be open for the second time, the following steps are executed: reclosing the precharge relay; or,

after the main negative relay is closed again, whether the pre-charging is successful or not is diagnosed and whether the external circuit of the power battery is short-circuited is identified according to preset logic conditions

Optionally, the execution flow module is specifically configured to:

after the pre-charging relay is closed again, whether the pre-charging is successful or not is diagnosed according to preset logic conditions, and whether an external circuit of the power battery is short-circuited is identified

In a third aspect, there is provided an electric vehicle including: a battery management system;

the battery management system is configured to perform the method of high voltage power up of any of the first aspects.

The embodiment of the application has the following advantages:

in the high-voltage power-on method, after the open circuit of the pre-charging relay or the open circuit of the main negative relay is determined for the first time, the pre-charging relay or the main negative relay is tried to be closed for multiple times, wherein after each time the pre-charging relay or the main negative relay is tried to be closed, whether the two relays are open circuit or not is diagnosed according to a preset strategy; by the method, the problem that the pre-charging relay and the main negative relay are not powered up and act can be solved.

After the fact that the pre-charging relay and the main negative relay are closed is determined for the first time, whether the pre-charging is successful or not is diagnosed according to preset logic conditions, and whether an external circuit of the power battery is short-circuited is identified; after the success of pre-charging is determined and the fact that the external circuit of the power battery is not short-circuited is identified, whether the primary main positive relay is open-circuited is diagnosed; by the method, the risk of short circuit of the external circuit of the power battery can be effectively intercepted.

After the open circuit of the main positive relay is determined for the first time, part of the high-voltage power-on flow is tried for many times, wherein after each part of the high-voltage power-on flow is tried, whether the main positive relay is open circuit is diagnosed; by the method, the problem that the main relay is electrified and not operated is solved.

And finally, after determining that the main positive relay is not opened, sending information of finishing the high-voltage power-on flow to the whole vehicle controller. In summary, by the method for closing the relay for multiple times or executing part of the high-voltage power-on flow for multiple times, the problem that the whole vehicle cannot be powered on to report faults caused by the fact that the relay is electrified and the faults cannot be powered on and need maintenance of the trailer, and further extremely poor experience is brought to a user is solved, and therefore the experience of the user is improved greatly. In addition, the risk of short circuit of the external circuit of the power battery is effectively intercepted, and the risk of short circuit thermal runaway of the power battery is avoided, so that the safety of the whole vehicle and the human body is improved. The high-voltage power-on method has higher practicability.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:

FIG. 1 is a flow chart of a method of high voltage power up according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a power cell system and motor system according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of an embodiment of the present invention including a first bleeder switch;

fig. 4 is a schematic diagram of a structure including a second bleeder switch and bleeder resistor according to an embodiment of the present invention.

Detailed Description

In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

The inventor researches and discovers that in the existing high-voltage power-on method of the electric automobile, the related relay is only allowed to act once, and due to consistency difference of the existing relay products, burrs or surface roughness of the surface of a moving part are abnormal, and the relay has the risk of interference of parts during the action, the faults such as non-action, non-actuation or actuation delay of the power-on of the relay coil can be caused. However, such faults can cause failure of the entire vehicle to report faults, and when failure of the entire vehicle to report occurs, maintenance of the trailer is generally required, which definitely brings poor experience to users.

In addition, the current high-voltage power-on method can well intercept the risk of short circuit of the internal circuit of the power battery, but cannot well intercept the risk of short circuit of the external circuit of the power battery (namely load short circuit), if the external circuit of the power battery is short-circuited, the risk of thermal runaway of the short circuit of the power battery can be caused by closing the main relay, and the fire burning of the power battery can be caused when serious, so that the safety of the whole vehicle and the human body is endangered.

In order to solve the above problems, the inventors have made extensive studies and actual measurements to creatively propose a high-voltage power-up method according to the present invention, and the high-voltage power-up method according to the present invention will be described in detail below.

Referring to fig. 1, a flowchart of a method for high voltage power up according to an embodiment of the present invention is shown, the method comprising:

step 101: after the pre-charge relay is opened or the main negative relay is opened, the pre-charge relay is closed in a plurality of times or the main negative relay is closed in a plurality of times, wherein the pre-charge relay is diagnosed whether to be opened or not according to a preset strategy during the plurality of times of the pre-charge relay closing, and the main negative relay is diagnosed whether to be opened or not according to the preset strategy during the plurality of times of the main negative relay closing.

In the method for high-voltage power-on of the electric automobile, generally, after the electric automobile is started, a whole vehicle controller sends a high-voltage power-on starting instruction to a battery management system, and after the battery management system receives the instruction, the battery management system starts high-voltage power-on operation according to a preset high-voltage power-on flow.

Since the priming flow is first initiated, there are generally two power-up sequences for the priming flow: the first is to close the pre-charging relay and then close the main negative relay; the second is to close the main negative relay first and then to close the pre-charging relay. Whichever power-up sequence is used, the battery management system needs to perform the adhesion diagnosis of the main positive relay, the adhesion diagnosis of the main negative relay and the adhesion diagnosis of the pre-charging relay. Only if the main positive relay is not adhered, the main negative relay is not adhered, and the pre-charging relay is not adhered, the pre-charging relay or the main negative relay can be closed.

Taking the first power-up sequence as an example: after the precharge relay is closed for the first time, a diagnosis needs to be made as to whether the precharge relay is open. Only after the fact that the pre-charging relay is not opened and the main negative relay is not adhered is the main negative relay closed for the first time, whether the first pre-charging is successfully diagnosed and whether an external circuit is short-circuited are identified.

If the pre-charging relay is determined to be open for the first time, the battery management system does not report that the whole vehicle cannot be electrified, but tries to close the pre-charging relay for many times, and in the period of trying to close the pre-charging relay for many times, whether the pre-charging relay is open or not is diagnosed according to a preset strategy. For example: the open circuit diagnosis of the pre-charging relay can be carried out after each attempt of closing the pre-charging relay; or continuously trying to close the pre-charging relay for preset times, and then diagnosing whether the pre-charging relay is open or not.

For example: the number of times set is 3, then after the first determination that the precharge relay is open, the battery management system attempts to close the precharge relay a second time (this is the first time the battery management system closes the precharge relay among the set number of times 3). After the second time of trying to close the pre-charging relay, whether the pre-charging relay is open or not is diagnosed, if the pre-charging relay is determined to be not open at the time, the pre-charging relay is normally closed, and the next step is carried out according to the flow.

However, if the result of the second pre-charge relay open circuit diagnosis is still that the pre-charge relay is open circuit, the battery management system tries to close the pre-charge relay for the third time (this is the second time the battery management system closes the pre-charge relay in the set number of times 3). After the third time of trying to close the pre-charging relay, whether the pre-charging relay is open or not is diagnosed for the third time, if the pre-charging relay is determined to be not open at this time, the pre-charging relay is normally closed, and the next step is carried out according to the flow.

If the result of the third pre-charge relay open circuit diagnosis is still that the pre-charge relay is open, then the battery management system tries to close the pre-charge relay for the fourth time (this is the third time the battery management system closes the pre-charge relay in the set number of times 3). After the fourth attempt is made to close the pre-charging relay, whether the fourth pre-charging relay is open or not is diagnosed, if the pre-charging relay is determined to be not open at this time, the pre-charging relay is normally closed, and the next step is carried out according to the flow. If the result of the open circuit diagnosis of the fourth pre-charging relay is still that the pre-charging relay is open circuit, the battery management system can report that the whole vehicle cannot be powered on to the whole vehicle controller, and the whole vehicle controller can send an alarm after receiving the result, so that a user knows and carries out subsequent processing operation.

Also for example: the preset number of times is 3, then the battery management system may continuously attempt to close the precharge relay 3 times, that is, the battery management system continuously turns on and off the precharge relay 3 times, and after the 3 rd time, the power-on state is maintained, and then the diagnosis is performed as to whether the precharge relay is open. The continuous action is multiple times, which is beneficial to the interference of the moving rod of the relay, thereby better solving the problems of power-on failure, non-actuation or actuation delay and the like of the relay coil.

In any time, after the pre-charging relay is successfully closed and the main negative relay is not adhered, the main negative relay can be closed for the first time, and then whether the main negative relay is open-circuited or not can be diagnosed for the first time.

If the primary negative relay is determined to be open for the first time, the battery management system does not report that the whole vehicle cannot be electrified, but tries to close the primary negative relay for many times because the pre-charging relay is normal.

Similar to the step of closing the pre-charging relay in multiple attempts, for multiple attempts to close the main negative relay, the diagnosis of whether the main negative relay is open is performed once every time the main negative relay is tried to be closed; or continuously trying to close the main negative relay for a plurality of times, and diagnosing whether the main negative relay is open or not again. Assuming that the number of times is 2, after the pre-charging failure is determined for the first time, the main negative relay is tried to be closed twice, and whether the main negative relay is open-circuited or not is diagnosed once every time the main negative relay is tried to be closed once; or continuously trying to close the main negative relay for 2 times, and diagnosing whether the main negative relay is open or not. If the main negative relay is determined to be not open at any time, namely the main negative relay is closed, performing the next step according to the flow; if the main relay is still determined to be open after the main relay is closed twice, the battery management system can report that the whole vehicle cannot be electrified to the whole vehicle controller, and the whole vehicle controller can give an alarm after receiving the alarm, so that a user knows and carries out subsequent processing operation.

For the second power-on sequence, after the primary negative relay is determined to be open, after each attempt of closing the primary negative relay, diagnosing whether the primary negative relay is open or not is carried out; or after determining that the main negative relay is open for the first time, continuously attempting to close the main negative relay for preset times, and diagnosing whether the main negative relay is open; after determining that the main relay and the negative relay are not opened and the main relay is not adhered, closing the pre-charging relay for the first time, and diagnosing whether the pre-charging relay is opened or not; after determining that the pre-charging relay is open for the first time, diagnosing whether the pre-charging relay is open or not after each time of trying to close the pre-charging relay; or after the open circuit of the pre-charging relay is determined for the first time, continuously attempting to close the pre-charging relay for preset times, and then diagnosing whether the pre-charging relay is open circuit.

In the second power-on sequence, the main negative relay is closed firstly, then the pre-charging relay is closed, and after the main negative relay is first powered on, if the main negative relay is opened, the main negative relay is tried to be closed for a plurality of times, and the open-circuit diagnosis of the main negative relay is carried out according to a preset strategy until the main negative relay is closed or still opened (alarm after still opened), after the main negative relay is closed, the pre-charging relay is closed for the first time, if the pre-charging relay is opened, the pre-charging relay is tried to be closed for a plurality of times, and the open-circuit diagnosis of the pre-charging relay is carried out according to the preset strategy until the pre-charging relay is closed or still opened (alarm after still opened). For the second power-up sequence, reference may be made to the method of the first power-up sequence, and redundant description is omitted.

Through the mode, the problem that the coil of the pre-charging relay and the main negative relay is electrified and does not act accidentally is effectively solved.

Step 102: after the pre-charging relay and the main negative relay are determined to be closed for the first time, whether the pre-charging is successfully diagnosed and whether an external circuit of the power battery is short-circuited are identified according to preset logic conditions.

In step 102, as long as it is determined that both the pre-charge relay and the main negative relay are closed successfully, the battery management system performs a diagnosis of whether the pre-charge is successful or not according to a preset logic condition, and at the same time, identifies whether the external circuit of the power battery is shorted. The method for identifying whether the external circuit of the power battery is short-circuited or not specifically comprises the following steps:

step S1: detecting whether a current with a stable current value exists in the pre-charging loop or not;

step S2: detecting whether a second voltage between a second end of the main positive relay and a first end of the main negative relay is far smaller than a first voltage between the first end of the main positive relay and the first end of the main negative relay;

step S3: alternatively, detecting whether the second voltage is near zero volts;

step S4: the method comprises the steps that under the condition that a current with a stable current value exists in a pre-charging loop, and the second voltage is far smaller than the first voltage, or the current with the stable current value exists in the pre-charging loop, and the second voltage is close to zero volt, the short circuit of an external circuit of the power battery is identified, and otherwise, the short circuit of the external circuit of the power battery is identified; the second end of the main positive relay is one end connected with the load end, the first end of the main positive relay is one end connected with the positive electrode of the power battery, and the first end of the main negative relay is one end connected with the negative electrode of the power battery.

The method of identifying whether the power cell external circuit is shorted can be better understood in conjunction with the schematic diagram of the power cell system and motor system shown in fig. 2. In fig. 2, the second end of the main positive relay is the point C, the first end of the main positive relay is the point a, and the first end of the main negative relay is the point B. The second voltage is the CB point voltage, and the first voltage is the AB point voltage.

If the external circuit has a short circuit, a current with a stable current value is definitely present in the pre-charging loop, the current value is basically stable and cannot drop exponentially, and the voltage at the CB point is far smaller than the voltage at the AB point, or the voltage at the CB point is close to 0V. If the pre-charging loop has a current with stable current value and the CB point voltage is far smaller than the AB point voltage, the battery management system identifies that the external circuit of the power battery is short-circuited; alternatively, if the pre-charge loop has a constant current and the CB point voltage is near 0V, the battery management system also recognizes that the power cell external circuit is shorted. Otherwise, the power battery external circuit is identified as not being shorted.

For example: the voltage of the power battery is 800V, the AB point voltage is 800V, if the CB point voltage is only 200V or below 200V, and the pre-charging loop has current with stable current value, the battery management system identifies that the external circuit of the power battery is short-circuited, otherwise, the external circuit of the power battery is not short-circuited. It should be noted that the CB point voltage is far smaller than the AB point voltage, which is determined according to the well-known knowledge of those skilled in the art. In general, the external circuit short circuit of the power battery comprises direct short circuit of the positive electrode to the negative electrode of the external circuit, or the positive electrode of the external circuit is short-circuited to the ground and the negative electrode of the external circuit is short-circuited to the ground, so that when the external circuit short circuit of the power battery occurs, the voltage of the CB point is definitely low, and even the voltage can be directly 0V.

If the external circuit of the power battery is short-circuited, the main positive relay cannot be closed, so that the risk of the external circuit of the power battery is effectively intercepted in the mode.

For a successful diagnosis of priming: an exemplary method is: detecting whether a current with exponentially reduced current value exists in the pre-charging loop or not; detecting whether the second voltage is equal to the first voltage; and under the condition that the current value of the pre-charging loop is exponentially reduced or the second voltage is equal to the first voltage, determining that the pre-charging is successful, otherwise, determining that the pre-charging is failed.

For example: the voltage of the power battery is 800V, the AB point voltage is 800V, if the CB point voltage is 800V, or although the CB point voltage does not reach 800V, the current value of the pre-charging loop is exponentially reduced (the final CB point voltage still reaches 800V), then the battery management system determines that the pre-charging is successful, otherwise, the battery management system determines that the pre-charging is failed.

In addition, if the external circuit of the power battery is identified to be short-circuited, the pre-charging is affirmed to fail, the pre-charging failure is directly determined, at the moment, the battery management system needs to disconnect the pre-charging relay and the main negative relay and send a first alarm signal to the whole vehicle controller, and the first alarm signal characterizes the short-circuit fault of the external circuit of the power battery, so that a user or an maintainer can conveniently carry out subsequent processing.

If it is recognized that the external circuit of the power battery is not shorted, but the pre-charge failure is determined by the foregoing method, then since the pre-charge relay and the main negative relay are normally closed, there may be pre-charge failure caused by other factors, such as: the connectors of the power battery system and the load system are loosened, the circuit is broken, and the like. At the moment, the battery management system also needs to disconnect the pre-charge relay and the main negative relay and send a second alarm signal to the whole vehicle controller, and the first alarm signal characterizes that the current fault is other fault types except the short circuit fault of the external circuit of the power battery, so that a user or an maintainer can conveniently carry out subsequent processing.

Step 103: and determining that the pre-charging is successful, identifying that the external circuit of the power battery is not short-circuited, and diagnosing whether the primary main relay is open-circuited or not.

Only if the pre-charging is successful and the external circuit of the power battery is identified to be not short-circuited, the battery management system can close the main positive relay, the main positive relay is closed for the first time by the battery management system, after the main positive relay is closed for the first time, the pre-charging relay needs to be opened by the battery management system, and then whether the main positive relay is open-circuited for the first time is diagnosed by the battery management system.

The method for diagnosing whether the main positive relay is open circuit is as follows: after the main positive relay is closed, the battery management system sends a signal representing the end of the high-voltage power-on flow to the whole vehicle controller, the whole vehicle controller can enter a vehicle driving mode after receiving the signal, and when the vehicle driving mode is entered, the second voltage drops at a high speed, and then the battery management system can determine that the main positive relay is open. This method essentially puts the main positive relay open circuit diagnosis after the high-voltage up-current process is finished, and the vehicle has entered the driving mode to determine whether the main positive relay is open or not, which brings bad driving experience to the user.

Based on this problem, the inventors creatively propose a method of determining whether a main positive relay is open or not open in a high-voltage power-on flow. That is, the method of performing the first time main positive relay open circuit diagnosis includes:

step T1: and executing the bus capacitor active discharging flow.

After the main positive relay is closed, the battery management system does not send a signal representing the end of the high-voltage power-on process to the whole vehicle controller, but executes the bus capacitor active discharging process, and further determines whether the main positive relay is open or not according to the change condition of the voltage of the bus capacitor end during active discharging. The bus capacitor active discharging flow is implemented by the following three methods, namely, step T1a, step T1b and step T1 c:

Step T1a: sending a discharge instruction to the motor controller, so that the motor controller controls the upper bridge arm and the lower bridge arm to be conducted according to the discharge instruction, and then energy of the bus capacitor is discharged through a first discharge loop, wherein the first discharge loop is as follows: and a discharge loop formed by passing through the upper bridge arm from one end of the bus capacitor, flowing through the motor winding and returning to the other end of the bus capacitor through the lower bridge arm.

The battery management system sends a discharge instruction to the motor controller, the motor controller receives the discharge instruction and then controls the upper bridge arm and the lower bridge arm to be conducted, when the upper bridge arm and the lower bridge arm are conducted, the bus capacitor, the upper bridge arm, the lower bridge arm and the motor winding form a closed loop, so that energy on the bus capacitor after the pre-charging is successful can flow through the motor winding from one end of the bus capacitor through the upper bridge arm, and then returns to the other end of the bus capacitor through the lower bridge arm to discharge.

With reference to fig. 2, after receiving the bleeder instruction, the motor controller (not shown in fig. 2) controls the upper bridge arm and the lower bridge arm to be conducted, and after the pre-charging is successful, the energy on the bus capacitor flows through the motor winding from one end of the bus capacitor through the upper bridge arm, and then returns to the other end of the bus capacitor through the lower bridge arm to perform bleeder.

Step T1b: the first bleeder switch is controlled to be conducted so that energy of the bus capacitor is discharged through a second bleeder circuit, and the second bleeder circuit refers to: and a discharging loop formed by returning one end of the bus capacitor to the other end of the bus capacitor through the first discharging switch and the pre-charging resistor.

In the second discharging method, the battery management system does not send an instruction to the motor controller, but directly controls the first discharging switch to be conducted, when the first discharging switch is conducted, the bus capacitor, the first discharging switch and the pre-charging resistor form a closed loop, so that energy on the bus capacitor after the pre-charging is successful can be discharged from one end of the bus capacitor through the first discharging switch and the pre-charging resistor, and the energy returns to the other end of the bus capacitor.

The second bleed method requires the addition of a bleed switch between the pre-charge resistor and the main negative relay. Referring to fig. 3, a schematic structural diagram including a first bleeder switch is shown. One end of the first bleeder switch is connected with the pre-charging resistor and the pre-charging relay respectively, and the other end of the first bleeder switch is connected with the main negative relay and the bus capacitor respectively. The battery management system (not shown in fig. 3) controls the first bleeder switch to be conducted, and energy on the bus capacitor after the pre-charging is successful returns to the other end of the bus capacitor to be discharged through the first bleeder switch and the pre-charging resistor from one end of the bus capacitor. The method has the advantages that only the first bleeder switch is added, the motor controller, the upper bridge arm, the lower bridge arm and the motor winding are not used for bleeder, the control logic is simplified, and the service lives of the motor controller, the upper bridge arm, the lower bridge arm and the motor winding are indirectly prolonged. And this first bleeder switch can be directly integrated in the battery system, does not occupy other physical space.

Step T1c: and controlling the second bleeder switch to be conducted so as to enable the energy of the bus capacitor to be discharged through a third bleeder circuit, wherein the third bleeder circuit refers to: and a bleeder circuit formed by returning one end of the bus capacitor to the other end of the bus capacitor through the second bleeder switch and the bleeder resistor.

In the third method, similar to the second method, the battery management system does not send an instruction to the motor controller, but directly controls the second bleeder switch to be conducted, when the second bleeder switch is conducted, the bus capacitor, the second bleeder switch and the bleeder resistor form a closed loop, and then energy on the bus capacitor after the pre-charging is successful can be returned to the other end of the bus capacitor for bleeder through the second bleeder switch and the bleeder resistor from one end of the bus capacitor.

The third bleed method requires an additional bleed resistor and a second bleed switch to be added to the battery system. Referring to fig. 4, a schematic structural diagram is shown containing a second bleeder switch and bleeder resistor. The second bleeder switch is connected in series with the bleeder resistor and then connected in parallel with the bus capacitor. The battery management system (not shown in fig. 3) controls the second bleeder switch to be conducted, and energy on the bus capacitor after the pre-charging is successful returns to the other end of the bus capacitor to be discharged through the second bleeder switch and the bleeder resistor from one end of the bus capacitor. In the method, the second bleeder switch and the bleeder resistor are independently arranged outside the battery system, so that a certain physical space is occupied, and the method is beneficial to later maintenance and overhaul. After the bleeder switch or the bleeder resistor is in a problem, the battery system is directly replaced or maintained without disassembling the battery system, so that a convenient maintenance and overhaul mode is provided for users and maintainers. It should be noted that, the control of the second bleeder switch may be implemented by the battery management system, or may be implemented by another controller or manager on the vehicle, or the like, except that, if not implemented by the battery management system, it is necessary to send an instruction to the controller or manager by the battery management system to cause the controller or manager to control the second bleeder switch to be closed.

Step T2: detecting the change condition of the voltage of the bus capacitor terminal after the bus capacitor actively discharges;

step T3: and when the change condition meets a preset condition, determining that the main positive relay is open.

By the method of step T1, the discharging of the bus capacitor can be performed, and after the discharging of the bus capacitor is started, the voltage change condition of the bus capacitor terminal is continuously detected, and the voltage change condition of the CB point in fig. 2, 3 and 4 is continuously detected, wherein the voltage of the bus capacitor terminal is substantially the second voltage. And when the change condition meets a preset condition, determining that the main positive relay is open. The preset conditions are: the CB point voltage slowly decreases until it is below a certain voltage threshold. If the voltage of the end of the bus capacitor is slowly reduced until the voltage is lower than a certain voltage threshold value after the bus capacitor is released, determining that the main positive relay is opened; if the voltage of the detection bus capacitor terminal is not reduced after the bus capacitor is discharged, or is not lower than the voltage threshold although the voltage is reduced, the main positive relay is determined to be not opened.

Step 104: after the open circuit of the main positive relay is determined for the first time, a part of high-voltage power-on flow is tried to be executed for many times, wherein after each time of trying to execute the part of high-voltage power-on flow, whether the main positive relay is open circuit is diagnosed, and the part of high-voltage power-on flow is as follows: in all the high-voltage power-on flows, part of the preamble flows are: and performing a flow before the flow of diagnosing whether the main positive relay is open.

After passing through step 103, if it is determined for the first time that the main positive relay is open, it is necessary to perform the partial high voltage power up process several times, wherein after each attempt to perform the partial high voltage power up process, a diagnosis is made as to whether the main positive relay is open. The multiple-attempt closing of the main positive relay is different from the multiple-attempt closing of the pre-charging relay and the main negative relay, and the direct multiple-attempt closing cannot be performed, because the pre-charging relay is opened at the moment, the voltage of a bus capacitor can be low, if the main positive relay is directly closed, extremely high current can be generated, the impact relay and load end equipment can be impacted, and faults endangering the safety of vehicles and personnel, such as explosion, ignition and the like can be caused when the faults are serious. The multiple attempts to close the main positive relay are essentially multiple attempts to perform part of the high voltage power up flow. For the first power-up sequence, a plurality of attempts to execute a partial high-voltage power-up current process specifically include two main methods:

the first broad category of methods:

after the primary positive relay is determined to be open for the first time, the pre-charging relay is closed again because of the need of re-charging; after the pre-charging relay is closed again, the main negative relay is normally closed at the moment, so that whether the pre-charging is successful or not can be diagnosed and whether the external circuit of the power battery is short-circuited or not can be identified according to preset logic conditions. In general, since it has been determined that the main negative relay is not opened, the external circuit of the power battery is not shorted, and thus, the pre-charge can be completed only by re-closing the pre-charge relay. However, the pre-charging relay may be opened after the pre-charging relay is re-closed, and if the pre-charging relay is opened, the pre-charging relay is closed according to the method of closing the pre-charging relay through multiple attempts.

The following steps are similar to steps 102-103, and after the success of pre-charging is determined and the fact that the external circuit of the power battery is not short-circuited is identified, the main positive relay is closed for the second time; after the main positive relay is closed for the second time, the pre-charging relay is opened again, and whether the main positive relay is open-circuited for the second time is diagnosed; after the second determination that the main positive relay is still open, the steps are performed: the precharge relay is reclosed.

It will be appreciated that if the result of the second primary positive relay open circuit diagnosis is that the primary positive relay is not open circuit, then step 105 is performed without performing the steps: the precharge relay is reclosed.

The second broad category of methods:

based on the consideration of safer and more reliable, after the primary positive relay is determined to be open for the first time, the primary negative relay is directly disconnected; the connection between the battery system and the load end is completely disconnected, and the high-voltage power-on flow is restarted.

After the main negative relay is opened, similarly to steps 101 to 103, the pre-charging relay is closed again, and if the pre-charging relay is opened, the pre-charging relay is tried to be closed for a plurality of times. After the pre-charging relay is closed again, the pre-charging relay and the main negative relay are not adhered, and the main negative relay is closed again; and after the main negative relay is closed again, carrying out diagnosis on whether the pre-charging is successful or not and identifying whether an external circuit of the power battery is short-circuited or not according to preset logic conditions. At this time, if the main negative relay is opened, the main negative relay is tried to be closed a plurality of times according to the aforementioned method.

The following method is the same as the first general method: after the pre-charging is determined to be successful and the external circuit of the power battery is identified to be not short-circuited, closing the main positive relay for the second time; after the main positive relay is closed for the second time, the pre-charging relay is opened again, and whether the main positive relay is open-circuited for the second time is diagnosed; after the open circuit of the main positive relay is determined for the second time, the following steps are executed: the main negative relay is turned off. Similarly, if the result of the second primary positive relay open circuit diagnosis is that the primary positive relay is not open circuit, then step 105 is performed without performing the steps of: the main negative relay is turned off. It will be appreciated that the second broad class of methods is safer, more reliable, but takes a slightly longer time than the first broad class of methods.

For the second power-up sequence, the main negative relay is closed first, so the method is similar to the second general method, and specifically includes:

after the primary positive relay is determined to be open for the first time, the primary negative relay is disconnected; after determining that the pre-charge relay and the main negative relay are not adhered, closing the main negative relay again instead of closing the pre-charge relay again; after the main negative relay is closed again, the pre-charging relay is closed again; after the pre-charging relay is closed again, whether the pre-charging is successful or not is diagnosed according to preset logic conditions, whether the external circuit of the power battery is short-circuited is identified, and after the pre-charging is successful and the external circuit of the power battery is not short-circuited is identified, the main positive relay is closed for the second time; after the main positive relay is closed for the second time, the pre-charging relay is opened again, and whether the main positive relay is open-circuited for the second time is diagnosed; after the open circuit of the main positive relay is determined for the second time, the following steps are executed: the main negative relay is turned off. Similarly, if the result of the second primary positive relay open circuit diagnosis is that the primary positive relay is not open circuit, then step 105 is performed without performing the steps of: the main negative relay is turned off. It will be appreciated that this method is safer and more reliable than the first general class of methods described above, but takes a somewhat longer time.

In the foregoing steps 101 to 104, the number of times of the multiple attempts is determined according to the required time of the entire high-voltage power-up, and in general, the entire high-voltage power-up process is preferably completed within 3 seconds, so that the user experience is better, and the shorter the time is, the better the time is. If the time for the entire high voltage current process to complete exceeds 10 seconds, the user experience will be poor, so the number of attempts can be determined based on this time. For example: the time for closing the precharge relay and the main negative relay by multiple attempts is short, can be set to 3 times or more than 3 times, and the time for closing the main positive relay by multiple attempts is slightly long, can be set to 2 times or 3 times, and the like. The specific times can be obtained through a large number of tests before the whole vehicle is delivered and used.

Step 105: and after determining that the main positive relay is not opened, sending information of finishing the high-voltage power-on flow to the whole vehicle controller.

According to the high-voltage power-on flow, after the main positive relay is determined to be not opened, the battery management system sends a signal representing the end of the high-voltage power-on flow to the whole vehicle controller, and after the whole vehicle controller receives the signal, the electric vehicle is controlled to enter a vehicle driving mode, and a user can start to drive in gear.

In summary, through the method of steps 101 to 105, the problem that the whole vehicle cannot report telegram caused by the fact that the relay is electrified and does not act is effectively solved, the risk of short circuit of the external circuit of the power battery is effectively intercepted, the user experience is greatly improved, and meanwhile safety of the whole vehicle and the human body is improved.

Based on the above-mentioned method for high-voltage power-up, the embodiment of the invention also provides a device for high-voltage power-up, which comprises:

Optionally, the main positive relay open circuit diagnosis module includes:

Optionally, the multi-attempt closure module is specifically configured to:

detecting whether the second voltage is near zero volts;

detecting whether the second voltage is equal to the first voltage;

Optionally, the execution submodule is specifically configured to:

Optionally, the execution submodule is configured to:

Optionally, the execution flow module is specifically configured to:

Based on the above-mentioned high-voltage power-on method, the embodiment of the invention also provides an electric automobile, which comprises: a power battery management system for performing the method of high voltage power up as described in any one of steps 101-105.

Through the embodiment, in the high-voltage power-on method of the invention, the main positive relay, the main negative relay and the pre-charging relay can be all tried to be closed for a plurality of times. The problem that the whole vehicle cannot report the fault caused by the fact that the relay is electrified and does not act is effectively solved, the problem that the vehicle cannot be electrified and needs to be maintained by a trailer, and further extremely poor experience is brought to a user is solved, and therefore the experience of the user is greatly improved. Meanwhile, a brand new method for diagnosing whether the main positive relay is open is provided, so that whether the main positive relay is open can be determined before the high-voltage power-on flow is finished. In addition, the risk of short circuit of the external circuit of the power battery is effectively intercepted, and the risk of short circuit thermal runaway of the power battery is avoided, so that the safety of the whole vehicle and the human body is improved. The high-voltage power-on method has higher practicability.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiment and all such alterations and modifications as fall within the scope of the embodiments of the invention.

Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or terminal device comprising the element.

The foregoing has outlined rather broadly the more detailed description of the invention in order that the detailed description of the invention that follows may be better understood, and in order that the present principles and embodiments may be better understood; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.

Claims

1. A method of high voltage power up, the method comprising:

after the open circuit of the pre-charging relay or the open circuit of the main negative relay is determined for the first time, the pre-charging relay is tried to be closed for a plurality of times or the main negative relay is tried to be closed for a plurality of times, wherein, the open circuit diagnosis of the pre-charging relay is carried out according to a preset strategy during the period of the repeated attempt to be closed for the pre-charging relay, and the open circuit diagnosis of the main negative relay is carried out according to the preset strategy during the period of the repeated attempt to be closed for the main negative relay; the preset strategy comprises the following steps: after determining that the pre-charging relay is open for the first time, diagnosing whether the pre-charging relay is open or not after each attempt of closing the pre-charging relay is made; or after the open circuit of the pre-charging relay is determined for the first time, continuously attempting to close the pre-charging relay for preset times, and then diagnosing whether the pre-charging relay is open circuit;

after the fact that the pre-charging relay is not opened and the main negative relay is not adhered is determined for the first time, the main negative relay is closed for the first time, and whether the main negative relay is opened or not is diagnosed for the first time; or after the primary negative relay is determined to be open for the first time, continuously attempting to close the primary negative relay for preset times, and then diagnosing whether the primary negative relay is open; or,

The preset strategy comprises the following steps: after the primary negative relay is determined to be open for the first time, diagnosing whether the primary negative relay is open or not after each attempt to close the primary negative relay is carried out; or after the primary negative relay is determined to be open for the first time, continuously attempting to close the primary negative relay for preset times, and then diagnosing whether the primary negative relay is open;

after determining that the pre-charging relay is open for the first time, diagnosing whether the pre-charging relay is open or not after each attempt to close the pre-charging relay; or after the open circuit of the pre-charging relay is determined for the first time, continuously attempting to close the pre-charging relay for preset times, and then diagnosing whether the pre-charging relay is open circuit;

after the fact that the pre-charging relay and the main negative relay are both closed is determined for the first time, whether pre-charging is successful or not is diagnosed according to preset logic conditions, and whether an external circuit of the power battery is short-circuited is identified; the preset logic conditions include: detecting whether a current with a stable current value exists in the pre-charging loop or not;

Detecting whether a second voltage between a second end of the main positive relay and a first end of the main negative relay is far smaller than a first voltage between the first end of the main positive relay and the first end of the main negative relay; alternatively, detecting whether the second voltage is near zero volts;

after the fact that the pre-charging relay and the main negative relay are both closed is determined for the first time, detecting whether current with exponentially reduced current values exists in the pre-charging loop or not;

detecting whether the second voltage is equal to the first voltage;

determining that the pre-charging is successful when the current with exponentially reduced current value exists in the pre-charging loop or the second voltage is equal to the first voltage, otherwise, determining that the pre-charging is failed;

the second end of the main positive relay is one end connected with a load end, the first end of the main positive relay is one end connected with the positive electrode of the power battery, and the first end of the main negative relay is one end connected with the negative electrode of the power battery;

after the open circuit of the main positive relay is determined for the first time, a part of high-voltage power-on flow is tried to be executed for many times, wherein after each attempt is executed for the part of high-voltage power-on flow, whether the main positive relay is open circuit is diagnosed, and the part of high-voltage power-on flow is as follows: reclosing the pre-charge relay after the primary positive relay is determined to be open for the first time;

after the primary positive relay is determined to be open for the second time, the following steps are executed: reclosing the precharge relay; or after the primary positive relay is determined to be open for the first time, the primary negative relay is disconnected;

after the main negative relay is closed again, whether the pre-charging is successful or not is diagnosed and whether an external circuit of the power battery is short-circuited is identified according to preset logic conditions;

after the primary positive relay is determined to be open for the second time, the following steps are executed: opening the main negative relay; or, the partial high-voltage power-on flow is as follows:

after the primary positive relay is determined to be open for the second time, the following steps are executed: opening the main negative relay;

2. The method of claim 1, wherein making a diagnosis of whether the main positive relay is open comprises:

executing a bus capacitor active discharging process;

3. The method of claim 2, wherein performing a bus capacitor active bleed procedure comprises:

4. The method of claim 2, wherein performing a bus capacitor active bleed procedure comprises:

5. The method of claim 1, wherein after determining that the pre-charge was successful and identifying that the power cell external circuit was not shorted, performing a first primary positive relay open circuit diagnostic comprises:

6. An electric automobile, characterized in that it comprises: a battery management system;

the battery management system is adapted to perform the method of high voltage power up as claimed in any one of claims 1-5.