WO2018103604A1

WO2018103604A1 - Power output control method and device, and power feedback control method and device

Info

Publication number: WO2018103604A1
Application number: PCT/CN2017/114452
Authority: WO
Inventors: 游祥龙
Original assignee: 郑州宇通客车股份有限公司
Priority date: 2016-12-05
Filing date: 2017-12-04
Publication date: 2018-06-14
Also published as: CN108162968A

Abstract

A power output control method and device and a power feedback control method and device are provided to obtain, according to a temperature and a SOC of a power battery, maximum allowable output power and maximum allowable charging power, compare the same to actual power of a vehicle to obtain maximum allowable output power of the power battery, and control, according to a comparison result, the power battery. The control method employs active control to ensure an optimal state of a vehicle power requirement, and prevent overcharge and over-discharge of the power battery, thereby preventing damages to the power battery, ensuring a normal input or output of the power battery.

Description

Power output control method and device, power feedback control method and device

Technical field

The invention relates to a power output control method and device, a power feedback control method and device, and belongs to the technical field of power control of a pure electric vehicle.

Background technique

In recent years, new energy vehicles have maintained a good momentum of development. The automakers have injected a lot of manpower and resources into relevant technology research and development. With the new energy buses and group cars being put into the market, it is a sign that this new vitality is The rise of the automotive industry. Accelerating the cultivation and development of energy-saving and new energy vehicles is not only an effective mitigation of energy and environmental pressure, but also an urgent task to promote the sustainable development of the automobile industry. With the introduction of subsidies and preferential policies for new energy vehicles by the national ministries and commissions, automakers and battery factories have adjusted their respective development strategies, researched and developed new models, and laid the foundation for large-scale industrialization of new energy vehicles.

The power supply system is one of the core components of new energy vehicles. Although the development of electric vehicles has made great progress, further breakthroughs are still needed in the development of key technologies, especially the safe driving of vehicles and battery protection. In the past pure electric vehicles, the whole vehicle proposed power requirements according to actual working conditions, and the power supply system passively charged and discharged according to actual road conditions. If the actual charge and discharge current value exceeds the capacity of the battery itself, or the power supply system has an alarm message, the battery management system informs the entire vehicle through CAN communication, and the whole vehicle adopts a power reduction or parking mode to protect the battery. However, such vehicle driving and battery protection control methods have unavoidable drawbacks: First, this is an open-loop control method, the battery alarm information occurs before, after processing, the battery has been damaged to varying degrees; Second, the vehicle does not consider the battery cell consistency factor, there will be the risk of sudden anchoring, and the vehicle cannot be safely driven under any circumstances. Third, the battery management system estimates the SOC and the power limit estimate. Taking full account of the various states of the power system, there are certain abnormal phenomena such as SOC inaccuracy and SOC jump.

Summary of the invention

The object of the present invention is to provide a pure electric vehicle power output control method for solving the problem that a conventional pure electric vehicle power output control method causes damage to a power battery. The invention also provides a pure electric vehicle power output control device, a pure electric vehicle power feedback control method and a pure electric vehicle power feedback control device.

To achieve the above object, the present invention provides a power output control method for a pure electric vehicle, comprising the following steps:

(1) obtaining a corresponding maximum allowable output power value by looking up the table according to the current SOC information and temperature information of the power battery;

(2) Comparing the actual required power of the vehicle with the maximum allowable output power value of the power battery: if the actual required power is greater than the maximum allowable output power value, the vehicle is driven at the maximum allowable output power value; if the actual required power is less than or equal to the maximum allowable power Output power value, the vehicle is driven by the actual demand power;

The table is a correspondence table of SOC information, temperature information, and maximum allowable output power value.

First, the inventor obtained through analysis that the maximum allowable output power value of the power battery has a corresponding relationship with the SOC and temperature of the battery. Therefore, the maximum allowable output power value in this state can be obtained according to the SOC and temperature of the power battery, and then compared. The actual required power of the vehicle and the maximum allowable output power value of the power battery. If the actual required power is less than or equal to the maximum allowable output power value, then the actual demand power is used to drive the vehicle to ensure the optimal state of the vehicle power demand; If the actual required power is greater than the maximum allowable output power value, the vehicle is driven at the maximum allowable output power value to avoid over-discharging of the power battery, thereby avoiding damage to the power battery. Therefore, the control method is power active control, first obtaining the maximum allowable output power value of the power battery and the actual required power of the vehicle, and then controlling the power according to the relationship between the actual required power of the vehicle and the maximum allowable output power value, The control method can avoid damage to the power battery and ensure the normal output of the power battery.

Further, when the power battery fails, the corresponding maximum allowable output power value is reduced by half.

Further, the SOC of the power battery is the SOC of the single cell corresponding to the minimum cell voltage in the power battery.

The invention also provides a pure electric vehicle power feedback control method, comprising the following steps:

(1) obtaining a corresponding maximum allowable charging power value by looking up the table according to the current SOC information and temperature information of the power battery;

(2) Comparing the actual feedback power of the vehicle with the maximum allowable charging power value of the power battery: if the actual feedback power is greater than the maximum allowable charging power value, the maximum allowable charging power value is charged by the power battery; if the actual feedback power is less than or equal to the maximum When the charging power value is allowed, the actual battery is charged with the actual feedback power;

The table is a correspondence table of SOC information, temperature information, and maximum allowable charging power value.

Further, when the power battery fails, the corresponding maximum allowable charging power value is reduced by half.

Further, the SOC of the power battery is the SOC of the single cell corresponding to the maximum cell voltage in the power battery.

The present invention also provides a pure electric vehicle power output control apparatus comprising a memory, a processor, and a computer program stored in the memory and operable on the processor, the processor implementing the program to implement the following steps:

The invention also provides a pure electric vehicle power feedback control device, comprising a memory and a processor And a computer program stored in the memory and operable on the processor, the processor implementing the program to implement the following steps:

DRAWINGS

1 is a schematic diagram of the principle of a power output control method for a pure electric vehicle;

2 is a schematic diagram of the principle of a pure electric vehicle power feedback control method.

detailed description

Pure electric vehicle power output control method embodiment

The pure electric vehicle power output control method generally includes the following steps:

(2) Comparing the actual required power of the vehicle with the maximum allowable output power value of the power battery: if the actual required power is greater than the maximum allowable output power value, the vehicle is driven at the maximum allowable output power value; if the actual required power is less than or equal to the maximum allowable power The output power value drives the vehicle at the actual demand power.

Each step will be described in detail below.

First, the maximum allowable output power value is the maximum output power value that the power battery can safely use and does not affect the battery life in the current state. Therefore, the maximum allowable output power value can also be referred to as power. Limit.

In order to meet the optimal state of the vehicle power demand, at the same time, to ensure that the power battery does not have the risk of overcharge and overdischarge at any time, the maximum allowable output power value of the power battery is related to the battery state quantity. The state quantity of the battery refers to: SOC state, temperature state, cell voltage state, cell discrete state, and the like. Wherein, the SOC state refers to the remaining capacity of the battery, and the discharge capacity of the battery decreases as the SOC decreases; the temperature state refers to the environment in which the battery is used, and when the temperature is too high or too low, the charge and discharge capability of the battery is greatly increased. Decrease; the voltage state of the cell has a trend corresponding to the battery SOC under certain conditions. The lower the cell voltage of a single cell, the lower the SOC of the cell; the cell dispersion state, the reaction is the battery The consistency of the system cell voltage, according to the barrel effect, the overall discharge capacity of the power battery depends on the minimum cell voltage of the system and the SOC corresponding to the minimum cell voltage.

Therefore, when the vehicle is running normally, the power limit of the power battery is related to the SOC and the temperature. There is a one-to-one correspondence between the three, and a certain SOC has a power limit corresponding to a certain temperature, and the SOC When the temperature changes, the power limit is also changed accordingly. Therefore, a table can be made, which is a correspondence table of SOC, temperature and power limit. In the case where the SOC and the temperature are determined, the power limit in this case can be obtained by looking up the table. The correspondence between SOC, temperature and power limit is obtained by the battery manufacturer or the corresponding battery user through a long-term large number of experiments. Therefore, the corresponding relationship can be obtained through experiments, as shown in Tables 1, 2 and 3 below. The specific relationship is partially illustrated.

In addition, because of the barrel effect, the overall discharge capacity of the power battery depends on the minimum cell voltage in the power cell and the SOC corresponding to the minimum cell voltage. When the power battery is charging, in order to avoid overcharging of the battery, the maximum cell voltage is corrected to 100% of the SOC, and in the case of discharging, in order to avoid overdischarge of the battery, it depends on the SOC corresponding to the lowest cell voltage, which requires driving. During the process, the SOC corresponding to the highest cell voltage currently displayed is gradually and smoothly transitioned to the SOC corresponding to the lowest cell voltage. Therefore, in the embodiment, during the power battery discharge process, the SOC of the power battery is the SOC of the single battery corresponding to the internal minimum cell voltage, and if the detected SOC of the power battery corresponds to the minimum cell voltage, When there is a deviation in the SOC of the battery, the transition to the minimum SOC is gradually and smoothly performed, that is, the SOC of the single cell corresponding to the minimum cell voltage is taken as the SOC of the power battery. The SOC is selected in order to further prevent the power battery from being over-discharged. Of course, as a more general embodiment, the entire power battery can be used as a target, and the detection device can be used to detect the SOC of the entire power battery, and the directly detected SOC is used as the power. The SOC of the battery does not have to be affected by each individual battery.

Therefore, in any vehicle operating condition, the power limit of the power battery can be obtained according to the corresponding SOC and temperature and the corresponding relationship of the three.

The correspondence between the three is stored in the controller. In this embodiment, the vehicle controller is taken as an example. The vehicle controller realizes the power output control of the power battery. Taking the current state as an example, the vehicle controller obtains the power limit of the power battery in the current state according to the SOC and temperature of the current power battery. Then, compare the actual demand power of the vehicle with the power limit of the power battery in the current situation. Wherein, the actual required power can be obtained by the opening degree of the accelerator pedal, and the vehicle controller obtains the corresponding required power according to the opening degree of the accelerator pedal.

There are two relationships between the actual demand power and the power limit of the power battery, which are the case where the actual demand power is greater than the power limit, and the actual demand power is less than or equal to the power limit.

When the actual demand power is greater than the power limit, under the control of the vehicle controller, the actual power output of the power battery is the power limit of the power battery, and the vehicle is driven by the power. That is to say, the power supply is less than necessary, then, although the demand power of the vehicle is larger, in order to ensure the performance of the power battery and prevent overdischarge, the power battery can only provide the maximum allowable output power, that is, the power limit, the vehicle controller. The vehicle is controlled to drive with a power limit.

When the actual demand power is less than or equal to the power limit, under the control of the vehicle controller, the actual output power of the power battery is the actual demand power, and the vehicle is driven by the power. That is to say, if the power supply is greater than the demand, then the power battery can provide the actual required power to meet the requirements, and the vehicle controller controls the vehicle to drive at the actual required power.

Therefore, through this control method, not only can the optimal state of the vehicle's power demand be ensured; It is also possible to avoid overdischarge of the power battery.

In addition, when the power battery is in an alarm state, for example, when the power battery fails, the power limit of the power battery in each case needs to be reduced by 50%, that is, the new power limit is the original corresponding power limit. Half of the value, this control can protect battery safety. Moreover, it can also display in advance the meter, beep alarm, remind the driver to pay attention, and ensure the safe driving of the vehicle. Therefore, the alarm state is a state that occurs under special conditions, and the power limit is adjusted after the fault occurs.

Based on the above technical solution, an application example is given below.

Assume that the power battery of a pure electric vehicle has a rated voltage rating of 560 volts. The battery management system needs to estimate its own allowable discharge capacity from time to time. The power battery power limit is related to the SOC and temperature. The power limit at any time can be obtained by looking up the table between the above three. Since the output power of the power battery is proportional to the output current, the corresponding power is characterized by the current. The power limit is characterized below by the maximum allowable discharge current value of the power battery, ie, the discharge current limit. According to the opening degree of the accelerator pedal, the corresponding actual demand discharge current can be obtained. Moreover, as shown in Table 1 below, the power battery has different discharge current limits at different temperatures and different SOCs. For example, when the SOC is 90% and the temperature is 30 °C, look up the current discharge current limit of the power battery. The value is I7A.

Therefore, when the actual required discharge current is greater than the discharge current limit I7A, the discharge current limit I7A is used as the discharge current of the actual output of the power battery, and the vehicle controller drives the vehicle to travel with the power corresponding to the discharge current limit I7A. When the actual demand discharge current is less than or equal to the discharge current limit I7A, the actual demand discharge current is used as the discharge current of the actual output of the power battery, and the vehicle controller drives the vehicle to drive with the power corresponding to the actual demand discharge current. Figure 1 shows a specific embodiment of the discharge control process.

Therefore, through this control method, not only can the optimal state of the power demand of the whole vehicle be ensured; but also the over-discharge of the power battery can be avoided. In short, in order to avoid over-discharging the battery, the actual demand discharge current of the whole vehicle is less than or equal to I7A.

Table 1

Table 2 below gives some specific numerical relationships between the power battery discharge current limit, SOC, and temperature.

Table 2

For example, when the SOC is 90% and the temperature is 30 °C, according to Table 2, the current discharge current limit of the power battery is 300A. The discharge current limits of other SOCs and temperatures can be directly obtained according to the above table, or linear. Interpolation is obtained.

Moreover, when the power battery has alarm information, it is necessary to adjust the corresponding discharge current limit under the above conditions to 50%*I7, and reduce it to half of the original limit. The allowable discharge current limits at different temperatures and different SOCs can be obtained experimentally according to different battery manufacturers.

In addition, in order to achieve safe driving of the vehicle, in addition to adjusting the power battery power limit, if necessary, the battery management system needs to issue an alarm message and prompt information in the meter. When the power battery has undervoltage information, the battery management system issues an alarm message. The meter displays “The battery is too low and needs to be charged.” When the SOC is too low, the meter prompts “SOC is too low, need to be charged”; when the vehicle high voltage system is insulated When the resistance is too low, you need to indicate in the instrument that "the system insulation is low, you need to go back to the factory for maintenance", "the battery consistency difference is too large, need to be balanced maintenance", through the similar alarm information prompt, you can effectively remind the driver to prepare in advance to avoid The vehicle broke down due to a power battery failure.

The above method can be stored as a computer program in a memory in a pure electric vehicle power output control device and can be operated on a processor in a pure electric vehicle power output control device.

Pure electric vehicle power feedback control method embodiment

The pure electric vehicle power feedback control method generally includes the following steps:

(2) Comparing the actual feedback power of the vehicle with the maximum allowable charging power value of the power battery: if the actual feedback power is greater than the maximum allowable charging power value, the maximum allowable charging power value is charged by the power battery; if the actual feedback power is less than or equal to the maximum When the charging power value is allowed, the power battery is charged with the actual feedback power.

Each step will be described in detail below.

First, the maximum allowable charging power value is the maximum charging power value that the power battery can safely use and does not affect the battery life in the current state, so the maximum allowable charging power value may be referred to as a charging limit.

Then, similar to the above embodiment of the pure electric vehicle power output control method, the maximum allowable charging power value of the power battery has a corresponding relationship with the SOC and temperature of the power battery, and accordingly, the correspondence between the three can also be It is indicated by a relation table that, in the case where the SOC and the temperature are determined, the charging limit in this case can be obtained by looking up the table. Since the relationship between the three has been described in detail in the above embodiment of the power output control method, it will not be specifically described herein. In addition, the correspondence between the SOC, the temperature, and the charging limit is also obtained by the battery manufacturer or the corresponding battery user through a long-term experiment.

Moreover, similarly to the description in the embodiment of the pure electric vehicle power output control method described above, in order to further avoid overcharging of the power battery, the SOC of the power battery is the SOC of the single battery corresponding to the internal maximum cell voltage during the charging process of the power battery. . Of course, as a more general embodiment, it is also possible to use the detection device to detect the SOC of the entire power battery, and directly check the entire power battery. The measured SOC is used as the SOC of the power battery, and is not affected by each unit battery.

The correspondence between the three is stored in the controller. In this embodiment, the vehicle controller is taken as an example. The vehicle controller realizes the power feedback control of the power battery. Taking the current state as an example, the vehicle controller obtains the charging limit of the power battery in the current state according to the current SOC and temperature of the power battery. Then, compare the actual feedback power of the vehicle with the charging limit of the power battery in the current situation. The actual feedback power can be obtained by the degree of depression of the brake pedal, and the vehicle controller obtains the corresponding feedback power according to the degree of depression of the brake pedal.

There are two relationships between the actual feedback power and the charging limit of the power battery, namely, the case where the actual feedback power is greater than the charging limit, and the case where the actual feedback power is less than or equal to the charging limit.

When the actual feedback power is greater than the charging limit, the charging limit of the power battery is used as the actual feedback power of the power battery, and the vehicle controller uses the power as the power battery to charge, that is, under the control of the vehicle controller, The charging limit portion of the actual feedback power is charged into the power battery, and the remaining power in the actual feedback power except the charging limit can be consumed by the energy consuming circuit.

When the actual feedback power is less than or equal to the charging limit, the actual feedback power is used as the power battery charging, that is, when the actual feedback power is less than or equal to the charging limit, the actual feedback power can be fully charged into the power battery, then Under the control of the vehicle controller, the actual feedback power is fully charged into the power battery.

Therefore, through this control method, not only can the optimal state of the power demand of the whole vehicle be ensured; but also the overcharge of the power battery can be avoided.

In addition, when the power battery is in an alarm state, for example, when the power battery fails, it is necessary to reduce the charging limit of the power battery in each case by 50%, that is, the new charging limit is the original corresponding charging limit. Half of the value, this control can protect battery safety. Moreover, it can also display in advance the meter, beep alarm, remind the driver to pay attention, and ensure the safe driving of the vehicle. Therefore, the alarm state is a state that occurs under special conditions, and the power limit is adjusted after the fault occurs.

Based on the above technical solution, an application example is given below.

Assume that the power battery of a pure electric vehicle has a rated voltage rating of 560 volts. The battery management system needs to estimate its own allowable charging capability from time to time. The power battery charging limit is related to the SOC and the temperature. The charging limit at any time can be found according to the relationship between the above three. Since the charging power of the power battery is proportional to the charging current, the corresponding power is characterized by the current. The charging limit is characterized below by the maximum allowable charging current value of the power battery, ie the charging current limit. Taking Table 1 as an example, if the corresponding relationship between the charging limit, SOC and temperature in the charging state is also used, as shown in Table 1, the charging current limit allowed by the power battery at different temperatures and different SOCs, For example, when the SOC is 90% and the temperature is 30 °C, look up the table to find the current charging current limit of the power battery is I7A.

Therefore, when the actual charging current obtained according to the degree of depression of the brake pedal is greater than the charging current limit I7A, the vehicle controller controls the charging current limit I7A as the actual charging current of the power battery to be charged. When the actual charging current obtained according to the degree of depression of the brake pedal is less than or equal to the charging current limit I7A, the vehicle controller controls the obtained actual charging current as the actual charging current of the power battery, and charges it. Figure 2 shows a specific implementation of the charge control process.

Table 3 gives a partial specific numerical relationship between the power battery charge limit, SOC, and temperature.

table 3

For example, when the SOC is 90% and the temperature is 30 °C, according to Table 3, the current charging current limit of the power battery is 150A. The charging current limits of other SOCs and temperatures can be directly obtained according to the above table, or linear. Interpolation is obtained.

Therefore, through this control method, not only can the optimal state of the power demand of the whole vehicle be ensured; but also the overcharge of the power battery can be avoided. In short, in order to avoid overcharging the battery, the actual charging current of the vehicle must be Less than or equal to I7A.

Moreover, when the power battery has an alarm message, it is necessary to adjust the corresponding charging current limit under the above conditions to 50%*I7, and reduce it to half of the original limit. The allowable charging current limits at different temperatures and different SOCs can also be obtained experimentally according to different battery manufacturers.

Therefore, the pure electric vehicle power output control method and the power feedback control method provided above can overcome the drawbacks of the conventional vehicle control and battery management system. Considering the various factors of the power battery, combined with the whole vehicle, a closed-loop control method is adopted to avoid overcharging and over-discharging of the battery. Moreover, in order to improve the estimation accuracy of SOC time and time, the SOC estimation strategy adopts the scheme of minimum monomer voltage following during the whole vehicle driving process; at the same time, the power battery alarm information can be displayed on the instrument, promptly reminding the driver to pay attention to the matter, effectively avoiding the battery Vehicle breakdown caused by consistency factors or other alarm information.

The above method can be stored as a computer program in a memory in a pure electric vehicle power feedback control device and can be operated on a processor in a pure electric vehicle power feedback control device.

Specific embodiments have been given above, but the invention is not limited to the described embodiments. The basic idea of the present invention lies in the above basic scheme, and it is not necessary for the person skilled in the art to design various modified models, formulas and parameters according to the teachings of the present invention. Variations, modifications, alterations and variations of the embodiments may be made without departing from the spirit and scope of the invention.

Claims

A pure electric vehicle power output control method, characterized in that the method comprises the following steps:

(1) obtaining a corresponding maximum allowable output power value by looking up the table according to the current SOC information and temperature information of the power battery;

(2) Comparing the actual required power of the vehicle with the maximum allowable output power value of the power battery: if the actual required power is greater than the maximum allowable output power value, the vehicle is driven at the maximum allowable output power value; if the actual required power is less than or equal to the maximum allowable power Output power value, the vehicle is driven by the actual demand power;

The table is a correspondence table of SOC information, temperature information, and maximum allowable output power value.
The pure electric vehicle power output control method according to claim 1, wherein when the power battery fails, the corresponding maximum allowable output power value is decreased by half.
The pure electric vehicle power output control method according to claim 1, wherein the SOC of the power battery is the SOC of the single battery corresponding to the minimum cell voltage in the power battery.
A pure electric vehicle power feedback control method, characterized in that the method comprises the following steps:

(1) obtaining a corresponding maximum allowable charging power value by looking up the table according to the current SOC information and temperature information of the power battery;

(2) Comparing the actual feedback power of the vehicle with the maximum allowable charging power value of the power battery: if the actual feedback power is greater than the maximum allowable charging power value, the maximum allowable charging power value is charged by the power battery; if the actual feedback power is less than or equal to the maximum When the charging power value is allowed, the actual battery is charged with the actual feedback power;

The table is a correspondence table of SOC information, temperature information, and maximum allowable charging power value.
The pure electric vehicle power feedback control method according to claim 4, wherein when the power battery fails, the corresponding maximum allowable charging power value is decreased by half.
A pure electric vehicle power feedback control method according to claim 4, wherein The SOC of the power battery is the SOC of the single cell corresponding to the maximum cell voltage in the power battery.
A pure electric vehicle power output control device includes a memory, a processor, and a computer program stored in the memory and operable on the processor, wherein the processor executes the program to implement the following steps:

(1) obtaining a corresponding maximum allowable output power value by looking up the table according to the current SOC information and temperature information of the power battery;

(2) Comparing the actual required power of the vehicle with the maximum allowable output power value of the power battery: if the actual required power is greater than the maximum allowable output power value, the vehicle is driven at the maximum allowable output power value; if the actual required power is less than or equal to the maximum allowable power Output power value, the vehicle is driven by the actual demand power;

The table is a correspondence table of SOC information, temperature information, and maximum allowable output power value.
The pure electric vehicle power output control apparatus according to claim 7, wherein when the power battery fails, the corresponding maximum allowable output power value is decreased by half.
A pure electric vehicle power feedback control device includes a memory, a processor, and a computer program stored in the memory and operable on the processor, wherein the processor executes the program to implement the following steps:

(1) obtaining a corresponding maximum allowable charging power value by looking up the table according to the current SOC information and temperature information of the power battery;

(2) Comparing the actual feedback power of the vehicle with the maximum allowable charging power value of the power battery: if the actual feedback power is greater than the maximum allowable charging power value, the maximum allowable charging power value is charged by the power battery; if the actual feedback power is less than or equal to the maximum When the charging power value is allowed, the actual battery is charged with the actual feedback power;

The table is a correspondence table of SOC information, temperature information, and maximum allowable charging power value.
The pure electric vehicle power feedback control device according to claim 9, wherein when the power battery fails, the corresponding maximum allowable charging power value is decreased by half.