Power battery charging and discharging control method of on-line direct current driving system

Abstract

The invention provides a power battery charging and discharging control method of an online direct-current driving system. The power battery charging and discharging control method comprises a power battery charging and discharging control method in a driving state and a braking state of a powered vehicle. In the driving state of the powered vehicle, according to the driving required power of the powered vehicle, the power supply state of the wire net and the charge state of the power battery, whether the power battery needs to be discharged to participate in driving or not is judged and determined through a logical algorithm. In the braking state of the powered vehicle, according to the charge state of the power battery, whether the power battery needs to be subjected to kinetic energy recovery or net synchronous auxiliary charging or not is judged and determined through a logical algorithm. The performance of the power battery can be fully exerted, and the energy utilization efficiency of the on-line direct current driving system is improved.

Description

Technical Field

[0001] The present invention relates to the field of control methods for online direct current drive transportation systems, and in particular to a method for controlling charging and discharging of a power battery in an online direct current drive system. Background Art

[0002] The online DC drive transportation system is an extension of the technical concept of the electrified highway transportation system, and consists of a DC power supply network, an on-board pantograph, and an online DC drive power receiving vehicle. The DC power supply network includes a DC traction substation and a DC transmission network. The power receiving vehicle integrates the relatively mature production and research and development technologies of dual-source trackless buses and pure electric heavy trucks in my country. The on-board pantograph installed on the top of the vehicle contacts the overhead DC transmission line built above the transportation road to receive power, so that the vehicle can draw power from the power supply network online in real time according to the required power. The vehicle only needs to carry a small capacity power battery to meet the demand for short-distance pure electric driving after leaving the power supply network.

[0003] The online DC drive transportation system is applied in the field of highway freight. The transportation conditions are relatively complex. The electric vehicle frequently accelerates and brakes during transportation, which causes the system energy to be frequently transferred and converted. If the energy supply process of the electric vehicle is not reasonably controlled, a large amount of unnecessary power loss will occur. The single power supply capacity of the power supply network is not enough to meet the energy demand of the electric vehicle during rapid acceleration. Therefore, the power battery needs to intervene at the appropriate time to assist in powering the drive motor, and the kinetic energy of the electric vehicle during braking can also be recovered by the power battery. A reasonable design of the power battery charge and discharge control method can improve the energy utilization efficiency of the entire system during operation and further improve the economy of the system. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a power battery charge and discharge control method for an online DC drive system.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] A power battery charging and discharging control method for an online DC drive system, the specific steps are as follows:

[0007] Step 1: The controller determines the driving state of the electric vehicle, determines whether the electric vehicle is in a driving or braking state, and obtains the current driving power of the electric vehicle, the braking power of the electric vehicle, the power supply power of the line network, and the state of charge signal of the power battery. If the electric vehicle is in a driving state, it goes to step 2; if the electric vehicle is in a braking state, it goes to step 3;

[0008] Step 2: The controller determines whether the power battery needs to be discharged for driving according to the current driving power of the receiving vehicle, the power supply power of the line network and the charge state information of the power battery according to the logic algorithm, and determines the discharge power of the power battery;

[0009] Step three: The controller determines whether the power battery needs to recover kinetic energy or line-grid synchronous auxiliary charging based on the current braking power of the powered vehicle and the power battery charge status information according to the logic algorithm, and determines the charging power of the power battery.

[0010] The specific process of step one is as follows:

[0011] S101: The controller obtains the current network power supply P gs and power battery state of charge SOC;

[0012] S102: The controller obtains the required power signal P of the driving motor of the electric vehicle m , if the required power of the drive motor is P m is a positive value, it is determined that the electric vehicle is in the driving state and goes to step 2. If the required power P of the driving motor m If it is a negative value, it is determined that the powered vehicle is in a braking state and go to step 3.

[0013] The specific process of step 2 is as follows:

[0014] S201: If the required power P of the drive motor m Less than the upper limit of the power supply power P gs,max , then the required power P of the drive motor m All are powered by the power grid;

[0015] S202: If the required power P of the drive motor m Greater than the upper limit of the power supply power P gs,max , and the power battery state of charge SOC is greater than the preset minimum value SOC min , the controller issues a control instruction, the power battery starts the discharge state, and the discharge power P bs,dc The specific form is:

[0016] P bs,dc =P m -P gs,max

[0017] S203: If the required power P of the drive motor m Greater than the upper limit of the power supply power P gs,max , and the power battery state of charge SOC is less than the preset minimum value SOC min , then the required power P of the drive motor m Reduce to the upper limit of the power supply power Pgs,max equal;

[0018] The specific process of step three is as follows:

[0019] S301: If the power battery state of charge SOC is less than a preset maximum value SOC max , and the required power P of the drive motor m Greater than the maximum charging power P of the power battery bs,c,max , the controller issues a control instruction, the power battery starts charging, and the charging power P bs,c The specific form is:

[0020] P bs,c =P bs,c,max

[0021] S302: If the power battery state of charge SOC is less than a preset maximum value SOC max And greater than the preset minimum SOC min , and the required power P of the drive motor m Less than the maximum charging power P of the power battery bs,c,max , the controller issues a control instruction, the power battery starts charging, and the charging power P bs,c The specific form is:

[0022] P bs,c =|P m |

[0023] S303: If the power battery state of charge SOC is less than a preset minimum value SOC min , and the required power P of the drive motor m Less than the maximum charging power P of the power battery bs,c,max , the controller issues a control instruction, the power battery starts charging, and the network synchronous auxiliary charging is started at the same time, so that the power battery charging power reaches the maximum charging power P bs,c,max , charging power P bs,c The specific form is:

[0024] P bs,c =P bs,c,max =|P m |+P gs BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a flowchart of a method for controlling charging and discharging of a power battery in an online DC drive system. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0027] like Figure 1 As shown, a power battery charging and discharging control method for an online DC drive system, the specific steps are as follows:

[0028] Step 1: The controller determines the driving state of the electric vehicle, determines whether the electric vehicle is in a driving or braking state, and obtains the current driving power of the electric vehicle, the braking power of the electric vehicle, the power supply power of the line network, and the state of charge signal of the power battery. If the electric vehicle is in a driving state, it goes to step 2; if the electric vehicle is in a braking state, it goes to step 3;

[0029] Step 2: The controller determines whether the power battery needs to be discharged for driving according to the current driving power of the receiving vehicle, the power supply power of the line network and the charge state information of the power battery according to the logic algorithm, and determines the discharge power of the power battery;

[0030] Step three: The controller determines whether the power battery needs to recover kinetic energy or line-grid synchronous auxiliary charging based on the current braking power of the powered vehicle and the power battery charge status information according to the logic algorithm, and determines the charging power of the power battery.

[0031] The specific process of step one is as follows:

[0032] S101: The controller obtains the current network power supply P gs and power battery state of charge SOC;

[0033] S102: The controller obtains the required power signal P of the driving motor of the electric vehicle m , if the required power of the drive motor is P m is a positive value, it is determined that the electric vehicle is in the driving state and goes to step 2. If the required power P of the driving motor m If it is a negative value, it is determined that the powered vehicle is in a braking state and go to step 3.

[0034] The specific process of step 2 is as follows:

[0035] S201: If the required power P of the drive motor m Less than the upper limit of the power supply power P gs,max , then the required power P of the drive motor m All are powered by the power grid;

[0036] S202: If the required power P of the drive motor m Greater than the upper limit of the power supply power P gs,max , and the power battery state of charge SOC is greater than the preset minimum value SOC min , the controller issues a control instruction, the power battery starts the discharge state, and the discharge power P bs,dc The specific form is:

[0037] P bs,dc =P m -P gs,max

[0038] S203: If the required power P of the drive motor m Greater than the upper limit of the power supply power P gs,max , and the power battery state of charge SOC is less than the preset minimum value SOC min , then the required power P of the drive motor m Reduce to the upper limit of the power supply power P gs,max equal;

[0039] The specific process of step three is as follows:

[0040] S301: If the power battery state of charge SOC is less than a preset maximum value SOC max , and the required power P of the drive motor m Greater than the maximum charging power P of the power battery bs,c,max , the controller issues a control instruction, the power battery starts charging, and the charging power P bs,c The specific form is:

[0041] P bs,c =P bs,c,max

[0042] S302: If the power battery state of charge SOC is less than a preset maximum value SOC max And greater than the preset minimum SOC min , and the required power P of the drive motor m Less than the maximum charging power P of the power battery bs,c,max , the controller issues a control instruction, the power battery starts charging, and the charging power P bs,c The specific form is:

[0043] P bs,c =|P m |

[0044] S303: If the power battery state of charge SOC is less than a preset minimum value SOC min, and the required power P of the drive motor m Less than the maximum charging power P of the power battery bs,c,max , the controller issues a control instruction, the power battery starts charging, and the network synchronous auxiliary charging is started at the same time, so that the power battery charging power reaches the maximum charging power P bs,c,max , charging power P bs,c The specific form is:

[0045] P bs,c =P bs,c,max =|P m |+P gs .

Claims

1. A power battery charging and discharging control method for an online DC drive system, characterized in that: The specific steps are as follows: Step 1: The controller determines the driving state of the electric vehicle, determines whether the electric vehicle is in a driving or braking state, and obtains the current driving power of the electric vehicle, the braking power of the electric vehicle, the power supply power of the line network, and the state of charge signal of the power battery. If the electric vehicle is in a driving state, it goes to step 2; if the electric vehicle is in a braking state, it goes to step 3; Step 2: The controller determines whether the power battery needs to be discharged for driving according to the current driving power of the receiving vehicle, the power supply power of the line network and the charge state information of the power battery according to the logic algorithm, and determines the discharge power of the power battery; Step three: The controller determines whether the power battery needs to recover kinetic energy or line-grid synchronous auxiliary charging based on the current braking power of the powered vehicle and the power battery charge status information according to the logic algorithm, and determines the charging power of the power battery.

2. The power battery charge and discharge control method of an online DC drive system according to claim 1, characterized in that: The specific process of step one is as follows: S101: The controller obtains the current network power supply P gs and power battery state of charge SOC; S102: The controller obtains the required power signal P of the driving motor of the electric vehicle m , if the required power of the drive motor is P m is a positive value, it is determined that the electric vehicle is in the driving state and goes to step 2. If the required power P of the driving motor m If it is a negative value, it is determined that the powered vehicle is in a braking state and go to step 3.

3. The power battery charge and discharge control method of an online DC drive system according to claim 1, characterized in that: The specific process of step 2 is as follows: S201: If the required power P of the drive motor m Less than the upper limit of the power supply power P gs,max , then the required power P of the drive motor m All are powered by the power grid; S202: If the required power P of the drive motor m Greater than the upper limit of the power supply power P gs,max , and the power battery state of charge SOC is greater than the preset minimum value SOC min , the controller issues a control instruction, the power battery starts the discharge state, and the discharge power P bs,dc The specific form is: P bs,dc =P m -P gs,max S203: If the required power P of the drive motor m Greater than the upper limit of the power supply power P gs,max , and the power battery state of charge SOC is less than the preset minimum value SOC min , then the required power P of the drive motor m Reduce to the upper limit of the power supply power P gs,max equal.

4. The power battery charge and discharge control method of an online DC drive system according to claim 1, characterized in that: The specific process of step three is as follows: S301: If the power battery state of charge SOC is less than a preset maximum value SOC max , and the required power P of the drive motor m Greater than the maximum charging power P of the power battery bs,c,max , the controller issues a control instruction, the power battery starts charging, and the charging power P bs,c The specific form is: P bs,c =P bs,c,max S302: If the power battery state of charge SOC is less than a preset maximum value SOC max And greater than the preset minimum SOC min , and the required power P of the drive motor m Less than the maximum charging power P of the power battery bs,c,max , the controller issues a control instruction, the power battery starts charging, and the charging power P bs,c The specific form is: P bs,c =|P m | S303: If the power battery state of charge SOC is less than a preset minimum value SOC min , and the required power P of the drive motor m Less than the maximum charging power P of the power battery bs,c,max , the controller issues a control instruction, the power battery starts charging, and the network synchronous auxiliary charging is started at the same time, so that the power battery charging power reaches the maximum charging power P bs,c,max , charging power P bs,c The specific form is: P bs,c =P bs,c,max =|P m |+P gs 。

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