CN109334508B - Power battery charging and discharging protection method and device - Google Patents

Power battery charging and discharging protection method and device Download PDF

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CN109334508B
CN109334508B CN201811123672.6A CN201811123672A CN109334508B CN 109334508 B CN109334508 B CN 109334508B CN 201811123672 A CN201811123672 A CN 201811123672A CN 109334508 B CN109334508 B CN 109334508B
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power
limit value
charging
pedal position
position signal
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CN109334508A (en
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邓金涛
李华
张芳
韩福强
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Weichai Power Co Ltd
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Weichai Power Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/10—Vehicle control parameters
    • B60L2240/12—Speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/42—Drive Train control parameters related to electric machines
    • B60L2240/423—Torque
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2250/00—Driver interactions
    • B60L2250/26—Driver interactions by pedal actuation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

The application provides a charging and discharging protection method and a charging and discharging protection device for a power battery, wherein the charging and discharging protection method for the power battery is an active protection mode, the change rate of a driving speed control signal in the driving process is actively monitored, and then a corresponding charging and discharging power limit value is determined according to the change rate of the driving speed control signal. And converting the charge and discharge power limit value into a torque limit value of a motor in the locomotive. The torque of the final control motor is lower than or equal to the torque limit value. According to the process, the method monitors the change rate of the driving control signal, adjusts the torque limit value of the motor according to the change rate of the driving control signal, and controls the charge and discharge power limit value of the power battery by controlling the output torque of the motor, so that the phenomenon of over-charge or over-discharge of the power battery is prevented, and the service life of the power battery is prolonged.

Description

Power battery charging and discharging protection method and device
Technical Field
The invention belongs to the technical field of batteries, and particularly relates to a power battery charging and discharging protection method and device.
Background
With the vigorous popularization of national new energy automobiles, new energy automobiles are increasingly on the market, and energy storage devices commonly used by the new energy automobiles are mainly power batteries.
The charging and discharging process of the power battery is controlled by a Vehicle Control Unit (VCU), and the magnitude of the charging and discharging power cannot be autonomously controlled. The current common scheme is passive protection, namely power limitation or power reduction processing is carried out after the actual power exceeds the limit; the VCU carries out single limitation according to the power limiting value sent by the battery BMS, and the phenomenon of battery overcharge or overdischarge is easy to occur, so that the power battery is damaged, and the service life of the power battery is shortened.
Disclosure of Invention
In view of the above, the present invention provides a method and an apparatus for protecting charging and discharging of a power battery, which actively protect the power battery, prevent the power battery from being overcharged or overdischarged, and prolong the service life of the power battery.
In a first aspect, the present application provides a power battery charging and discharging protection method, which is applied to a locomotive, and the method includes:
acquiring the change rate of a running speed control signal in the running process of the locomotive, wherein the running speed control signal comprises an acceleration signal and a braking signal;
determining a charge and discharge power limit value of a power battery corresponding to a rate of change of the travel speed control signal;
converting the charging and discharging power limit value into a torque limit value of a motor in the locomotive;
and controlling the torque of the motor to be lower than or equal to the torque limit value so as to enable the charge and discharge power of the power battery to be lower than or equal to the charge and discharge power limit value.
Optionally, the acquiring a change rate of the running speed control signal during the running of the locomotive includes:
acquiring an accelerator pedal position signal at the current moment in the running process of the locomotive, and acquiring the change rate of the accelerator pedal position signal according to the accelerator pedal position signal at the current moment and the accelerator pedal position signal at the previous moment;
alternatively, the first and second electrodes may be,
the method comprises the steps of obtaining a brake pedal position signal at the current moment in the running process of the locomotive, and obtaining the change rate of the brake pedal position signal according to the brake pedal position signal at the current moment and the brake pedal position signal at the previous moment.
Alternatively, the determining the charge-discharge power limit value of the power battery corresponding to the rate of change of the running speed control signal includes:
when the change rate of the accelerator pedal position signal is greater than or equal to an accelerator change rate threshold value, determining a discharge power limit value as the maximum allowable discharge power of the power battery;
and when the discharge time length for discharging by adopting the maximum allowable discharge power is greater than or equal to the discharge time length threshold value, determining the discharge power limit value as the rated discharge power.
Alternatively, the determining the charge-discharge power limit value of the power battery corresponding to the rate of change of the running speed control signal includes:
and when the change rate of the accelerator pedal position signal is smaller than the accelerator change rate threshold value, determining the discharge power limit value as the rated discharge power.
Alternatively, the determining the charge-discharge power limit value of the power battery corresponding to the rate of change of the running speed control signal includes:
when the change rate of the brake pedal position signal is greater than or equal to a brake change rate threshold value, determining a charging power limit value as the maximum allowable charging power of the power battery;
and when the charging time length for charging by adopting the maximum allowable charging power is greater than or equal to the charging time length threshold value, determining the charging power limit value as the rated charging power.
Alternatively, the determining the charge-discharge power limit value of the power battery corresponding to the rate of change of the running speed control signal includes:
and when the change rate of the brake pedal position signal is smaller than a brake change rate threshold value, determining the charging power limit value as the rated charging power.
Optionally, the converting the charge and discharge power limit value into a torque limit value of a motor in the locomotive includes:
acquiring the sum of power consumption of each auxiliary machine in the locomotive;
calculating a power difference between the charge and discharge power limit value and the sum of the power consumption;
and calculating a torque value corresponding to the power difference value as a torque limit value of the motor according to a relation formula P-T n/9549 of power and torque, wherein P is power, T is torque, and n is the rotating speed of the motor.
In a second aspect, the present application further provides a power battery charging and discharging protection device applied to a vehicle control unit, the device includes:
the system comprises an acquisition module, a control module and a control module, wherein the acquisition module is used for acquiring the change rate of a running speed control signal in the running process of the locomotive, and the running speed control signal comprises an acceleration signal and a braking signal;
the determination module is used for determining a charging and discharging power limit value of the power battery corresponding to the change rate of the running speed control signal;
the conversion module is used for converting the charge-discharge power limit value into a torque limit value of a motor in the locomotive;
and the control module is used for controlling the torque of the motor to be lower than or equal to the torque limit value so as to enable the charge and discharge power of the power battery to be smaller than or equal to the charge and discharge power limit value.
Optionally, the obtaining module is specifically configured to:
acquiring an accelerator pedal position signal at the current moment in the running process of the locomotive, and acquiring the change rate of the accelerator pedal position signal according to the accelerator pedal position signal at the current moment and the accelerator pedal position signal at the previous moment;
alternatively, the first and second electrodes may be,
the method comprises the steps of obtaining a brake pedal position signal at the current moment in the running process of the locomotive, and obtaining the change rate of the brake pedal position signal according to the brake pedal position signal at the current moment and the brake pedal position signal at the previous moment.
In a third aspect, the present application also provides a vehicle control unit comprising: the charging and discharging protection method for the power battery comprises a storage unit and a processing unit, wherein the storage unit stores program instructions, and the program instructions are executed by the processing unit to realize the charging and discharging protection method for the power battery according to any one of the possible implementation manners of the first aspect.
Compared with the prior art, the technical scheme provided by the invention has the following advantages: the power battery charging and discharging protection method is an active protection mode, the change rate of a driving speed control signal in the driving process is actively monitored, and then a corresponding charging and discharging power limit value is determined according to the change rate of the driving speed control signal. And converting the charge and discharge power limit value into a torque limit value of a motor in the locomotive. The torque of the final control motor is lower than or equal to the torque limit value. According to the process, the method monitors the change rate of the driving control signal, adjusts the torque limit value of the motor according to the change rate of the driving control signal, and controls the charge and discharge power limit value of the power battery by controlling the output torque of the motor, so that the phenomenon of over-charge or over-discharge of the power battery is prevented, and the service life of the power battery is prolonged.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a flowchart of a power battery charging and discharging protection method according to an embodiment of the present disclosure;
fig. 2 is a flowchart of another power battery charging and discharging protection method provided in the embodiment of the present application;
fig. 3 is a flowchart of another power battery charging and discharging protection method provided in the embodiment of the present application;
fig. 4 is a block diagram of a power battery charging and discharging protection device according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, a flowchart of a power battery charging and discharging protection method according to an embodiment of the present application is shown, where the method is applied to a vehicle control unit VCU, and as shown in fig. 1, the method may include the following steps:
and S110, acquiring the change rate of the running speed control signal in the running process of the locomotive.
The running speed control signal comprises an acceleration signal and a braking signal, wherein the acceleration signal is an accelerator pedal position signal, and the braking signal is a brake pedal position signal.
In the running process of the locomotive, the VCU collects an accelerator pedal position signal and a brake pedal position signal and carries out proper filtering processing.
Then, obtaining the change rate of the accelerator pedal position signal according to the accelerator pedal position signal corresponding to the current moment and the accelerator pedal position signal corresponding to the last moment; similarly, the change rate of the brake pedal position signal is obtained according to the brake pedal position signal at the current moment and the brake pedal position signal at the previous moment.
And S120, determining a charging and discharging power limit value of the power battery corresponding to the change rate of the running speed control signal.
Selecting a corresponding charge-discharge power limit value according to the specific change rate, for example, selecting a maximum charge-discharge power limit value if the change rate is relatively large; if the rate of change is relatively small, the rated charge/discharge power limit value is selected.
In one embodiment of the application, a threshold value of the change rate of the position signal of the accelerator pedal and a threshold value of the change rate of the position signal of the brake pedal are preset, and if the change rate is greater than or equal to the corresponding threshold value of the change rate, the power battery is controlled to be charged and discharged with the maximum charging and discharging power; and if the change rate is smaller than the corresponding change rate threshold value, controlling the power battery to charge and discharge at the rated charge and discharge power. Here, the rate of change threshold is a positive number.
And S130, converting the charge and discharge power limit value into a torque limit value of a motor in the locomotive.
The power battery is passively discharged, and the released power is consumed by energy consumption components such as a motor and auxiliary machines in the locomotive, so that the power limitation of the power battery is realized by the limitation of VCU on the energy consumption components such as the motor and the auxiliary machines.
And after determining the limit value of the charge and discharge power of the power battery, converting the limit value of the charge and discharge power into an output torque value of the motor, namely a torque limit value, according to a relation formula between power and torque.
And S140, controlling the torque of the motor to be lower than or equal to the torque limit value so as to enable the charge and discharge power of the power battery to be smaller than or equal to the charge and discharge power limit value.
The output torque of the motor is controlled to be lower than or equal to the torque limit value, so that the charging and discharging power of the power battery is less than or equal to the charging and discharging power limit value, and the phenomenon of over-charging or over-discharging of the power battery is avoided.
The power battery charging and discharging protection method provided by the embodiment is an active protection mode, the change rate of the driving control signal is actively monitored, the torque limit value of the motor is adjusted according to the change rate of the driving control signal, the charging and discharging power limit value of the power battery is controlled by controlling the output torque of the motor, the phenomenon of over-charging or over-discharging of the power battery is prevented, and the service life of the power battery is prolonged.
Referring to fig. 2, a flowchart of another power battery charging and discharging protection method according to an embodiment of the present application is shown, and this embodiment will focus on a method for preventing over-discharge of a power battery during a discharging process. As shown in fig. 2, the method may include the steps of:
and S210, acquiring an accelerator pedal position signal at the current moment in the running process of the locomotive.
The VCU is capable of acquiring an accelerator pedal position signal during locomotive operation.
And S220, calculating the change rate of the accelerator pedal position signal according to the accelerator pedal position signal at the current moment and the accelerator pedal position signal at the previous moment.
For example, the difference between the accelerator pedal position signal at the current time and the accelerator pedal position signal at the previous time is calculated, and then the ratio of the difference to the accelerator pedal position signal at the current time is calculated to obtain the change rate of the accelerator pedal position signal. The rate of change of the accelerator pedal position signal may be positive or negative.
S230, judging whether the change rate of the accelerator pedal position signal is greater than or equal to an accelerator change rate threshold value or not; if so, go to S240; if not, S260 is performed.
The throttle change rate threshold is related to the performance parameters of the battery, and can be set according to actual requirements.
And S240, determining to discharge with the maximum allowable discharge power of the power battery, and recording the discharge time length of the power battery discharging with the maximum allowable discharge power.
The change rate of the accelerator pedal position signal is larger than or equal to the accelerator change rate threshold value, which indicates that the locomotive has a larger power demand, and under the condition, the maximum allowable discharge power of the power battery is adopted to control the power battery to discharge.
The maximum permitted discharge power is a performance parameter of the power battery, and the parameter is measured and marked on a nameplate when the power battery is shipped from a factory, for example.
And meanwhile, recording the discharge time of the power battery discharging by adopting the maximum allowable discharge power.
S250, judging whether the discharge time length is greater than or equal to a discharge time length threshold value, if so, executing S260; if not, return to execute S240.
And monitoring whether the discharge time of the power battery discharging at the maximum allowable discharge power exceeds a discharge time threshold. The discharge time period threshold is related to the performance of the power battery, and may be determined according to the working time of the power battery, for example, the power battery can be discharged with the maximum allowable discharge power.
And if the discharge time length of the discharge with the maximum allowable discharge power exceeds the discharge time length threshold value, switching to the discharge with the rated discharge power.
And S260, determining that the power battery is discharged at the rated discharge power.
And if the change rate of the accelerator pedal position signal is smaller than the accelerator change rate threshold value, determining the discharge power limit value as the rated discharge power of the power battery.
The rated discharge power is a performance parameter of the power battery, and the parameter is measured and marked on the nameplate when the power battery leaves a factory.
And S270, converting the discharge power limiting value into a torque limiting value of the motor.
The power battery is passively discharged, and the released power is consumed by energy consumption components such as a motor and auxiliary machines in the locomotive, so that the power limitation of the power battery is realized by the limitation of VCU on the energy consumption components such as the motor and the auxiliary machines in the locomotive.
In practice, since various auxiliary machines consume power in addition to the motor during the running of the locomotive, it is necessary to estimate the power consumption of each auxiliary machine.
PEAM＝PDC+PEPS+PEAC+PAIR+PWRM(formula 1)
Wherein, in formula 1, PEAMConsuming the sum of the powers P for the individual auxiliary unitsDCPower consumed for DC/DC converters, PEPSFor power-assisted steering pump power, PEACFor power, P, of air compressorAIRIs the power of the air conditioner PWRMPower for electric defrosting and warm air; the power consumption value of each auxiliary machine can be calculated from the operating voltage and current fed back by each auxiliary machine by taking P as UI.
Calculating a torque limit value T of the motor according to the formula 2MTLmt：
Figure BDA0001811838190000081
In formula 2, PLmtFor a discharge power limit value in which P is dischargedLmtIs a positive value, PEAMN is the motor speed, which is the sum of the power consumed by each auxiliary machine.
Because the measured motor speed n fluctuates in actual conditions, if the measured n is directly substituted into the formula 2, the calculated torque limit value T is obtainedMTLmtCorresponding fluctuation exists, and the shaking of the whole vehicle is extremely easy to cause, so that the rotating speed of the motor needs to be processed according to a formula 3:
Figure BDA0001811838190000082
in formula 3, nActFor the measured actual rotating speed of the motor, delta n is the motor rotating speed segmentation step length, and the delta n is determined according to the actual rotating speed measuring precision of the motor, wherein the higher the measuring precision is, the smaller the delta n is, and the lower the measuring precision is, the larger the delta n is.
And S280, controlling the output torque of the motor to be less than or equal to the torque limit value so as to enable the discharge power of the power battery to be less than or equal to the discharge power limit value.
The output torque of the motor is controlled to be less than or equal to the torque limit value, so that the discharge power of the power battery is less than or equal to the discharge power limit value.
The embodiment provides a power battery charge-discharge protection method, which includes monitoring the change rate of an accelerator pedal position signal, and determining the discharge power limit value of a power battery as the maximum allowable discharge power of the battery after the change rate exceeds an accelerator change rate threshold; and meanwhile, recording the discharge time length for discharging by adopting the maximum allowable discharge power, and switching to discharge by using the rated discharge power of the battery when the discharge time length exceeds a discharge time length threshold value. And if the throttle change rate threshold value is not exceeded, directly discharging at the rated discharge power of the battery. The method can ensure that the discharge power of the power battery meets the power requirement of the locomotive, and can prevent the power battery from being over-discharged, thereby prolonging the service life of the power battery.
Referring to fig. 3, a flowchart of another power battery charging and discharging protection method according to an embodiment of the present application is shown, and this embodiment will focus on a method for preventing overcharge of a power battery during charging. As shown in fig. 3, the method may include the steps of:
s310, in the running process of the locomotive, the position signal of the brake pedal at the current moment is obtained.
The VCU is capable of acquiring brake pedal position signals during locomotive operation.
And S320, calculating the change rate of the brake pedal position signal according to the brake pedal position signal at the current moment and the brake pedal position signal at the previous moment.
For example, the difference between the brake pedal position signal at the current time and the brake pedal position signal at the previous time is calculated, and then the ratio of the difference to the brake pedal position signal at the current time is calculated to obtain the change rate of the brake pedal position signal.
S330, judging whether the change rate of the brake pedal position signal is greater than or equal to a brake change rate threshold value or not; if so, go to S340; if not, S360 is performed.
The brake change rate threshold is related to performance parameters of the battery, and can be set according to actual requirements.
And S340, determining the limit value of the charging power as the maximum allowable charging power of the power battery, and recording the charging time length of the power battery charged with the maximum allowable charging power.
If the change rate of the brake position signal is larger than or equal to the brake change rate threshold value, the locomotive is indicated to have larger brake requirement, and in this case, the maximum allowable charging power of the power battery is used for controlling the power battery to be charged.
The maximum allowable charging power is a performance parameter of the power battery, and the parameter is measured and marked on a nameplate when the power battery is shipped from a factory, for example.
And meanwhile, recording the charging time length of the power battery charged by adopting the maximum allowable charging power.
S350, judging whether the charging time length is greater than or equal to a charging time length threshold value, if so, executing S360; if not, return to execute S340.
And monitoring whether the charging time length of the power battery which is charged at the maximum allowable charging power exceeds a charging time length threshold value. The charging duration threshold is related to the performance of the power battery itself, and may be determined according to the operating time of the power battery, for example, the power battery can be charged with the maximum allowable charging power.
And if the charging time length charged by the maximum allowable charging power exceeds the charging time length threshold value, switching to charging by the rated charging power.
And S360, determining the charging power limit value as the rated charging power.
And if the change rate of the brake pedal position signal is smaller than the brake change rate threshold value, determining the charging power limit value as the rated charging power of the power battery.
The rated charging power is a performance parameter of the power battery, and the parameter is measured and marked on the nameplate when the power battery leaves a factory.
And S370, converting the charging power limit value into a torque limit value of the motor.
The power battery is passively charged, and a part of the power battery is consumed by energy consumption components such as a motor and auxiliary machines in the locomotive, so that the power limitation of the power battery is realized by the limitation of the VCU on the energy consumption components such as the motor and the auxiliary machines.
Firstly, calculating according to formula 1 to obtain power consumption conditions of each auxiliary machine in the locomotive, namely calculating to obtain PEAM(ii) a Then, the torque limit value T of the motor is calculated according to the formula 2MTLmt(ii) a During charging of the power battery, the charging power limit value PLmtIs a negative value; the difference between the charging power limit value and the power consumption of each auxiliary machine is the final charging power limit value of the power battery, because PLmtIs a negative value so PLmtAnd PEAMIs equal to PLmtAbsolute value of (A) and PEAMThe sum of the absolute values of (a). I.e. | PLmt-PEAM|＝|PLmt|+|PEAM|。
And S380, controlling the torque of the motor to be less than or equal to the torque limit value so as to enable the charging power of the power battery to be less than or equal to the charging power limit value.
The torque of the motor is controlled to be less than or equal to the torque limit value obtained in S370, so that the power battery charging power is less than or equal to the charging power limit value.
The power battery charge-discharge protection method provided by the embodiment monitors the change condition of a brake pedal position signal, and determines that the charging power limit value of a power battery is the maximum allowable charging power of the battery when the change rate exceeds a brake change rate threshold value; and meanwhile, recording the charging time length for charging by adopting the maximum allowable charging power, and switching to charging by using the rated charging power when the charging time length exceeds the threshold value of the charging time length. And if the brake change rate threshold value is not exceeded, directly charging the battery at the rated charging power of the battery. The mode can ensure that the charging power of the power battery meets the braking requirement of the locomotive, simultaneously can prevent the power battery from being overcharged, and prolongs the service life of the power battery.
Corresponding to the embodiment of the power battery charging and discharging protection method, the application also provides an embodiment of a power battery charging and discharging protection device.
Referring to fig. 4, a block diagram of a power battery charging and discharging protection device according to an embodiment of the present application, which is applied to a vehicle control unit VCU of a vehicle, is shown, and as shown in fig. 4, the device may include: an acquisition module 110, a determination module 120, a conversion module 130 and a control module 140;
the obtaining module 110 is configured to obtain a change rate of a driving speed control signal during a driving process of the locomotive.
The running speed control signal comprises an acceleration signal and a brake signal; in the running process of the locomotive, the VCU collects an accelerator pedal position signal and a brake pedal position signal, and performs appropriate filtering processing, wherein the accelerator pedal position signal is an acceleration signal, and the brake pedal position signal is a brake signal.
The acquisition module is specifically configured to, when acquiring a rate of change of an accelerator pedal position signal: acquiring an accelerator pedal position signal at the current moment in the running process of the locomotive, and acquiring the change rate of the accelerator pedal position signal according to the accelerator pedal position signal at the current moment and the accelerator pedal position signal at the previous moment;
for example, the difference between the accelerator pedal position signal at the current time and the accelerator pedal position signal at the previous time is calculated, and then the ratio of the difference to the accelerator pedal position signal at the current time is calculated to obtain the change rate of the accelerator pedal position signal. The rate of change of the accelerator pedal position signal may be positive or negative.
The acquisition module is specifically configured to, when acquiring a rate of change of a brake pedal position signal: the method comprises the steps of obtaining a brake pedal position signal at the current moment in the running process of the locomotive, and obtaining the change rate of the brake pedal position signal according to the brake pedal position signal at the current moment and the brake pedal position signal at the previous moment.
The determination module 120 is used for determining the charge and discharge power limit value of the power battery corresponding to the change rate of the running speed control signal.
In an embodiment of the present application, the determining module 120 determines the discharge power limit value of the power battery according to the change rate of the accelerator pedal position signal obtained by the obtaining module, and the specific determination process is as follows:
judging whether the change rate of the position signal of the accelerator pedal is greater than or equal to an accelerator change rate threshold value or not, and if so, determining that the discharge power limit value is the maximum allowable discharge power of the power battery; if the discharge power is smaller than the rated discharge power, determining the discharge power limit value as the rated discharge power of the power battery;
when the discharge duration is greater than or equal to the discharge duration threshold, the discharge duration is switched to discharge with the rated discharge power of the battery.
In another embodiment of the present application, the determining module 120 determines the charging power limit value of the power battery according to the change rate of the brake pedal position signal obtained by the obtaining module, and the specific determination process is as follows:
judging whether the change rate of the brake pedal position signal is greater than or equal to a brake change rate threshold value or not, and if so, determining that the charging power limit value is the maximum allowable charging power of the power battery; and if the charging power limit value is smaller than the rated charging power of the power battery, determining the charging power limit value as the rated charging power of the power battery.
When the charging duration is greater than or equal to the charging duration threshold, the charging is switched to be performed with the rated charging power of the battery.
And the conversion module 130 is configured to convert the charge/discharge power limit value into a torque limit value of a motor in the locomotive.
Because the power battery is passively charged and discharged, the power limitation of the power battery is realized by the limitation of VCU on energy consumption components such as motors, auxiliary machines and the like in the locomotive. The charging power limit value is converted into an output torque limit value of the motor using the above equations 1 and 2, and the charging power limit value is converted into a torque limit value of the motor.
And the control module 140 is configured to control the torque of the motor to be lower than or equal to the torque limit value, so that the charge and discharge power of the power battery is smaller than or equal to the charge and discharge power limit value.
The control module is used for controlling the torque of the motor according to the torque limit value converted by the conversion module, so that the charging and discharging power of the power battery does not exceed the charging and discharging power limit value.
The power battery charging and discharging protection device provided by the embodiment is an active protection mode, actively monitors the change rate of the driving control signal, adjusts the torque limit value of the motor according to the change rate of the driving control signal, controls the charging and discharging power limit value of the power battery by controlling the output torque of the motor, prevents the phenomenon of over-charging or over-discharging of the power battery, and prolongs the service life of the power battery.
On the other hand, the application also provides a vehicle control unit VCU, which includes a storage unit and a processing unit, wherein the storage unit stores therein program instructions, and the program instructions, when executed by the processing unit, implement the power battery charging and discharging protection method provided in any one of the above embodiments.
While, for purposes of simplicity of explanation, the foregoing method embodiments have been described as a series of acts or combination of acts, it will be appreciated by those skilled in the art that the present invention is not limited by the illustrated ordering of acts, as some steps may occur in other orders or concurrently with other steps in accordance with the invention. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and modules referred to are not necessarily required by the invention.
It should be noted that, in the present specification, the embodiments are all described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other. For the device-like embodiment, since it is basically similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
The steps in the method of the embodiments of the present application may be sequentially adjusted, combined, and deleted according to actual needs.
The device and the modules and sub-modules in the terminal in the embodiments of the present application can be combined, divided and deleted according to actual needs.
In the several embodiments provided in the present application, it should be understood that the disclosed terminal, apparatus and method may be implemented in other manners. For example, the above-described terminal embodiments are merely illustrative, and for example, the division of a module or a sub-module is only one logical division, and there may be other divisions when the terminal is actually implemented, for example, a plurality of sub-modules or modules may be combined or integrated into another module, or some features may be omitted or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or modules, and may be in an electrical, mechanical or other form.
The modules or sub-modules described as separate parts may or may not be physically separate, and parts that are modules or sub-modules may or may not be physical modules or sub-modules, may be located in one place, or may be distributed over a plurality of network modules or sub-modules. Some or all of the modules or sub-modules can be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
In addition, each functional module or sub-module in the embodiments of the present application may be integrated into one processing module, or each module or sub-module may exist alone physically, or two or more modules or sub-modules may be integrated into one module. The integrated modules or sub-modules may be implemented in the form of hardware, or may be implemented in the form of software functional modules or sub-modules.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be 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. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus 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 apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. A power battery charging and discharging protection method is applied to a locomotive and is characterized by comprising the following steps:
acquiring the change rate of a running speed control signal in the running process of the locomotive, wherein the running speed control signal comprises an acceleration signal and a braking signal;
determining a charge and discharge power limit value of a power battery corresponding to a rate of change of the travel speed control signal;
converting the charging and discharging power limit value into a torque limit value of a motor in the locomotive;
and controlling the torque of the motor to be lower than or equal to the torque limit value so as to enable the charge and discharge power of the power battery to be lower than or equal to the charge and discharge power limit value.
2. The method of claim 1, wherein said obtaining a rate of change of a travel speed control signal during travel of the locomotive comprises:
acquiring an accelerator pedal position signal at the current moment in the running process of the locomotive, and acquiring the change rate of the accelerator pedal position signal according to the accelerator pedal position signal at the current moment and the accelerator pedal position signal at the previous moment;
alternatively, the first and second electrodes may be,
the method comprises the steps of obtaining a brake pedal position signal at the current moment in the running process of the locomotive, and obtaining the change rate of the brake pedal position signal according to the brake pedal position signal at the current moment and the brake pedal position signal at the previous moment.
3. The method of claim 2, wherein the determining a charge-discharge power limit value for a power battery corresponding to a rate of change of the travel speed control signal comprises:
when the change rate of the accelerator pedal position signal is greater than or equal to an accelerator change rate threshold value, determining a discharge power limit value as the maximum allowable discharge power of the power battery;
and when the discharge time length for discharging by adopting the maximum allowable discharge power is greater than or equal to the discharge time length threshold value, determining the discharge power limit value as the rated discharge power.
4. The method of claim 3, wherein the determining a charge-discharge power limit value for a power battery corresponding to a rate of change of the travel speed control signal comprises:
and when the change rate of the accelerator pedal position signal is smaller than the accelerator change rate threshold value, determining the discharge power limit value as the rated discharge power.
5. The method of claim 2, wherein the determining a charge-discharge power limit value for a power battery corresponding to a rate of change of the travel speed control signal comprises:
when the change rate of the brake pedal position signal is greater than or equal to a brake change rate threshold value, determining a charging power limit value as the maximum allowable charging power of the power battery;
and when the charging time length for charging by adopting the maximum allowable charging power is greater than or equal to the charging time length threshold value, determining the charging power limit value as the rated charging power.
6. The method of claim 5, wherein the determining a charge-discharge power limit value for a power battery corresponding to a rate of change of the travel speed control signal comprises:
and when the change rate of the brake pedal position signal is smaller than a brake change rate threshold value, determining the charging power limit value as the rated charging power.
7. The method of claim 1, wherein converting the charge-discharge power limit value to a torque limit value for a motor in the locomotive comprises:
acquiring the sum of power consumption of each auxiliary machine in the locomotive;
calculating a power difference between the charge and discharge power limit value and the sum of the power consumption;
and calculating a torque value corresponding to the power difference value as a torque limit value of the motor according to a relation formula P-T n/9549 of power and torque, wherein P is power, T is torque, and n is the rotating speed of the motor.
8. A power battery charge-discharge protection device, characterized in that, be applied to a vehicle control unit, the device includes:
the system comprises an acquisition module, a control module and a control module, wherein the acquisition module is used for acquiring the change rate of a running speed control signal in the running process of the locomotive, and the running speed control signal comprises an acceleration signal and a braking signal;
the determination module is used for determining a charging and discharging power limit value of the power battery corresponding to the change rate of the running speed control signal;
the conversion module is used for converting the charge-discharge power limit value into a torque limit value of a motor in the locomotive;
and the control module is used for controlling the torque of the motor to be lower than or equal to the torque limit value so as to enable the charge and discharge power of the power battery to be smaller than or equal to the charge and discharge power limit value.
9. The apparatus of claim 8, wherein the obtaining module is specifically configured to:
acquiring an accelerator pedal position signal at the current moment in the running process of the locomotive, and acquiring the change rate of the accelerator pedal position signal according to the accelerator pedal position signal at the current moment and the accelerator pedal position signal at the previous moment;
alternatively, the first and second electrodes may be,
the method comprises the steps of obtaining a brake pedal position signal at the current moment in the running process of the locomotive, and obtaining the change rate of the brake pedal position signal according to the brake pedal position signal at the current moment and the brake pedal position signal at the previous moment.
10. A vehicle control unit, characterized by comprising: the charging and discharging protection method for the power battery comprises a storage unit and a processing unit, wherein the storage unit stores program instructions, and the program instructions realize the charging and discharging protection method for the power battery according to any one of claims 1-7 when being executed by the processing unit.
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