Power control method for extended-range hybrid power system, and extended-range hybrid power system and crane

Abstract

Disclosed in the present invention is a power control method for an extended-range hybrid power system. The method comprises: after being powered on, a vehicle entering by default a system startup mode in which the vehicle is only driven by a power battery; determining whether the electric power of the vehicle is above or equal to an upper limit of a preset threshold value; if the electric power of the vehicle is above or equal to the upper limit of the preset threshold value, the vehicle entering a discharge mode and turning on a range extender, and in this case, the range extender working at a high power and the battery being discharged at a low power, otherwise, the vehicle exiting the discharge mode, and then determining whether the SOC of the battery is below a lower limit of the preset threshold value; if the SOC of the battery is below the lower limit of the preset threshold value, the vehicle switching to a charge sustaining mode in which the priority is given to the power required for charging the battery, thereby sustaining the SOC of the battery within a certain charge interval; and when the SOC of the battery is above the upper limit of the preset threshold value, the vehicle exiting the charge sustaining mode and keeping the system startup mode. In the present invention, adaptive power control is performed on a range extender in a targeted manner, such that the power requirements of a vehicle for traveling are met, and the energy recovery power is increased by using the range extender to perform regenerative braking, thereby improving the braking performance of the vehicle, and thus optimizing the range, fuel economy and energy recovery effect of a crane.

Description

Power control method and system of extended-range hybrid system and crane TECHNICAL FIELD

[0001] The present application relates to the field of hybrid system working machines, in particular to a power control method and system of an extended-range hybrid system and a crane. BACKGROUND

[0002] In recent years, the penetration rate of new energy vehicles has gradually increased, and the national recognition and reputation have been continuously improved. Green, energy-saving and environmental protection have become an important direction for the development and transformation of current cranes. The extended-range hybrid crane can realize the decoupling of the engine and the vehicle speed, and is suitable for the operation conditions of low-speed driving and frequent start-stop of cranes, and gradually becomes one of the important transitional configurations from traditional fuel to new energy. However, due to the reasons such as large overall mass of the crane, complex driving conditions, and low battery energy recovery power, the power control logic of the range extender of the crane cannot follow the experience of passenger cars and commercial vehicles, resulting in problems such as high system cost, short cruising range, and poor fuel-saving effect of the crane, which restricts the large-area promotion of the extended-range crane.

[0003] The existing range extender control method is as follows:

[0004] When the SOC of the power battery is high, the range extender is closed, and the power required for chassis driving is completely provided by the power battery, which requires that the long-term discharge power of the battery can cover the driving power. When the SOC of the battery is lower than the minimum limit value, the range extender is started to generate power. In some conditions such as sudden acceleration or climbing, the range extender is started to generate power, and the power generation power is controlled to follow the throttle demand power. When the energy recovery function is activated, the range extender is in a closed or 0 power control state, and the recovery power completely depends on the allowable capacity of the battery.

[0005] The following disadvantages exist:

[0006] The long-term discharge power of the battery needs to cover the driving power of the whole vehicle, the capacity of the battery is large, and the system cost is high;

[0007] The energy recovery power completely depends on the maximum charging power of the battery, and the brake pads are severely worn and the braking effect is poor when the vehicle drives down a long slope and brakes frequently;

[0008] The power control method of the range extender is single, the energy consumption is high, or the battery power preservation ability is poor.

[0009] SUMMARY

[0010] Invention purposes: In order to overcome the shortcomings of the prior art, the first purpose of the present application is to disclose a power control method of a range extending hybrid system, which defines a chassis range extending mode as four sub-modes, namely a system starting mode, a discharging mode, an electric quantity maintaining mode and a range extender reverse drag mode. The method controls the range extender and the battery to cooperate with each other to meet the vehicle driving demand, reduces the battery capacity and system cost, optimizes the working efficiency of the range extender, improves the high-speed cruising range through the range extender power control, optimizes the forced energy recovery effect when descending a long slope, increases the energy recovery power through the range extender reverse drag, and optimizes the vehicle braking effect;

[0011] The second purpose is to disclose a range extending hybrid system running to realize the power control method described above.

[0012] The third purpose is to disclose a crane adopting the range extending hybrid system described above.

[0013] Technical scheme: The power control method of the range extending hybrid system disclosed by the present application includes a system starting mode, a discharging mode, an electric quantity maintaining mode and a range extender reverse drag mode.

[0014] After the whole vehicle is powered on, it enters the system starting mode by default, at this time the range extender is in an off state and is only driven by the power battery.

[0015] It is judged whether the vehicle power consumption is greater than or equal to the upper limit of the preset threshold value:

[0016] If yes, the discharging mode is entered, the range extender is turned on, at this time the range extender works at high power and the battery discharges at low power to meet the power demand of the whole vehicle, and when the vehicle power consumption is less than the lower limit of the preset threshold value, the discharging mode is exited.

[0017] If no, it is judged whether the battery SOC is less than the lower limit of the preset threshold value, if yes, the electric quantity maintaining mode is switched to, at this time the range extender meets the vehicle driving power and mainly charges the battery SOC to maintain it in a certain electric quantity interval, and when the battery SOC is greater than the upper limit of the preset threshold value, the electric quantity maintaining mode is exited and the system starting mode is kept.

[0018] When the vehicle hill descent function is started and reverse drag braking is needed, the range extender is switched from the power generation mode to the reverse drag mode, and the range extender consumes energy as the whole vehicle load, at this time the maximum limit of the forced energy recovery power = the long-term maximum charging power of the battery + the maximum power consumption of the range extender.

[0019] When the system detects that the driver steps on the brake, the energy recovery power is obtained according to the opening degree of the brake pedal, and it is judged whether the range extender works as a load for reverse drag braking according to the size of the energy recovery power and the maximum charging power of the battery; when the energy recovery power is greater than the maximum charging power of the battery, the range extender starts reverse drag mode, and the range extender works at a certain power consumption; at this time, the power consumption of the range extender = energy recovery power - maximum charging power of the battery.

[0020] Further, in the discharging mode, in addition to the range extender working at several high-efficiency power points, an enhanced mode is additionally provided.

[0021] In the discharging mode, power statistics are performed according to the vehicle driving condition, the highest power point of the range extender is selected as the highest power point of the engine, and the highest power point of the range extender which can run for a long time in the normal mode is selected as the second highest power point of the range extender; when the slope is greater than a preset threshold value, or the battery SOC is less than a preset threshold value, or the vehicle speed is greater than a preset threshold value, the system directly enters the enhanced mode, and at this time, the range extender works at the highest power point and the second highest power point alternately for a period of time; when the slope is less than a preset threshold value, the battery SOC is greater than a preset threshold value, and the vehicle speed is less than a preset threshold value, the enhanced mode is exited.

[0022] Further, in the discharging mode, if the enhanced mode is not entered, the target power of the battery in the current mode is obtained according to the vehicle power consumption and the size of the battery SOC in combination with the battery characteristic parameters, and the target power of the range extender is calculated as follows:

[0023] Range extender target power = vehicle power consumption - battery target power in discharging mode

[0024] After the target power of the range extender is calculated, the output power of the range extender is obtained according to the selected several high-efficiency power points of the range extender by using the nearest neighbor principle.

[0025] When the vehicle power consumption is less than a preset threshold value, the system enters the starting mode; otherwise, the discharging mode is maintained.

[0026] Further, in the power maintenance mode, when the vehicle power consumption is greater than a preset threshold value, the discharging mode is entered.

[0027] Otherwise, in combination with the battery characteristic parameters, the target power of the battery in the power maintenance mode is obtained according to the size of the battery pack temperature and the battery SOC, taking the balance of the battery power as the target, and the target power of the range extender is calculated as follows:

[0028] Range extender target power = vehicle power consumption - battery target power in power maintenance mode

[0029] After the target power of the range extender is calculated, the output power of the range extender is obtained according to the selected several high-efficiency power points of the range extender by using the nearest neighbor principle.

[0030] If the battery SOC is greater than a preset threshold, the system enters a start mode, otherwise, the power maintaining mode is maintained.

[0031] A range-extending hybrid system, comprising a range extender composed of an engine and a generator, a power battery, a multi-in-one controller connected to the range extender and the power battery, an electric motor connected to the multi-in-one controller, a drive train connected to the electric motor and wheels, and the power control method is implemented.

[0032] Advantages: Compared with the prior art, the advantages of the application are:

[0033] 1. In the discharge mode, the subsequent possible high-power demand working condition is predicted, and the enhanced mode is entered in advance to improve the power generation of the range extender and reserve power for the subsequent possible high-power driving working condition in advance.

[0034] 2. In the power maintaining mode, the battery SOC is maintained in a certain balance state to prolong the battery life.

[0035] 3. In the discharge mode and the power maintaining mode, the range extender and the battery cooperate with each other to drive the vehicle, which reduces the battery capacity and the system cost, increases the high-speed cruising range, and expands the operation transfer range of the crane.

[0036] 4. When the vehicle is descending a long slope, the range extender is switched from the power generation mode to the reverse drag mode, which breaks the limitation of the long-term charging power of the battery during energy recovery, improves the forced energy recovery effect, increases the cruising range, prevents the brake pad from overheating, reduces the friction loss, increases the service life of the parts, and improves the economy of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0037] Fig. 1 is a schematic diagram of the range-extending hybrid power system of the crane according to the application.

[0038] Fig. 2 is a control flow chart of the range extender during normal driving.

[0039] Fig. 3 is a control method flow chart of the range extender in the reverse drag mode. DETAILED DESCRIPTION

[0040] The technical solutions of the application will be further described below in combination with the drawings and examples.

[0041] As shown in Fig. 1, a range-extending hybrid power system for a crane, comprising a range extender composed of an engine and a generator, a power battery, a multi-in-one controller connected to the range extender and the power battery, an electric motor connected to the multi-in-one controller, a drive train connected to the electric motor and wheels.

[0042] The application optimizes the power control method of the range extender, coordinates the power distribution of the range extender and the battery, meets the power demand of vehicle driving, reduces the capacity of the battery, and thus reduces the system cost. The fuel consumption is reduced when driving at low speed, and the battery power is maintained at a healthy level; when driving at high speed or high power, the range extender starts the enhancement mode in advance to maximize the power generation of the range extender and increase the cruising range; when the vehicle is driving down a long slope, the battery is preferentially charged to recover energy, and when the capacity of the battery is exceeded, additional energy can be recovered by starting the range extender reverse drag mode. Through the reverse drag effect of the range extender, the energy recovery effect is improved, and the frequency of using brake pads is reduced, and the braking effect is optimized.

[0043] The application defines the chassis range extension mode as four sub-modes, namely system startup mode, discharge mode, power maintenance mode and range extender reverse drag mode.

[0044] System startup mode: enter this mode by default, mainly used when the vehicle starts and the battery SOC is greater than the lower limit of the battery charge interval, at this time the power demand of the vehicle is low, which is completely provided by the battery, and the range extender is in the off state.

[0045] Discharge mode: mainly used for high-speed driving or high-power driving (acceleration or climbing conditions), at this time the range extender and the power battery jointly participate in driving, and the range extender works at a high-power efficient operating point to reduce the battery discharge power and meet the power demand of the vehicle.

[0046] Power maintenance mode: mainly used for urban low-speed driving conditions, at this time the range extender meets the vehicle driving power while the battery charging demand power is mainly used to maintain the battery SOC within a certain power interval.

[0047] Range extender reverse drag mode: mainly used for vehicle driving down a long slope, mainly for energy recovery by charging the battery, and the range extender reverse drag is used as an auxiliary vehicle braking mode to optimize the braking effect.

[0048] After the vehicle is powered on, the system startup mode is entered by default, at this time the range extender is in the off state and is only driven by the power battery;

[0049] Determine whether the vehicle power consumption is greater than or equal to the upper limit of the preset threshold:

[0050] If yes, enter the discharge mode and start the range extender, at this time the range extender works at high power and the battery discharges at low power to meet the power demand of the vehicle driving, and when the vehicle power consumption is less than the lower limit of the preset threshold, the discharge mode is exited;

[0051] If not, it is judged whether the battery SOC is less than the lower limit of the preset threshold, if yes, it is switched to the power maintaining mode, at this time, the range extender meets the vehicle driving power, and the demand power of the battery charging is mainly used to maintain the battery SOC in a certain power interval, when the battery SOC is greater than the upper limit of the preset threshold, the power maintaining mode is exited, and the system starting mode is kept.

[0052] In the discharging mode, in addition to the range extender working at several high-efficiency power points, an enhanced mode is additionally set: the power is counted according to the crane driving condition, the highest power point of the engine is taken as the highest power point of the range extender, and the highest power point of the range extender capable of long-time operation in the conventional mode is taken as the second highest power point of the range extender, when the slope is greater than a preset threshold or the battery SOC is less than a preset threshold or the vehicle speed is greater than a preset threshold, the system directly enters the enhanced mode, at this time, the range extender alternately works at the highest power point and the second highest power point for a certain period of time, that is, the range extender first works at the highest power point for a period of time, then switches to the second highest power point for a period of time, and then switches back to the highest power point for a period of time, and the two working modes are repeatedly alternated. When the slope is less than the preset threshold, the battery SOC is greater than the preset threshold, and the vehicle speed is less than the preset threshold, the enhanced mode is exited. This mode not only guarantees the reliability of the range extender, but also maximizes the power generation of the range extender.

[0053] The application is described by taking several high-efficiency power points in sequence as an example.

[0054] SOC---state of charge

[0055] The vehicle power consumption is the sum of the driver's throttle demand power, the electrical loss power, the mechanical loss power and the power of each high-voltage component.

[0056] As shown in Fig. 2:

[0057] System starting mode:

[0058] It is mainly used for starting and the condition that the battery SOC is high, and the vehicle demand power is low, at this time, if the other two modes are not entered, that is, the default mode is entered, the engine working in the low-efficiency area is avoided, and the energy consumption of the range extender crane is reduced. At this time, the power battery alone drives the vehicle, and the range extender is in the closed state.

[0059] Discharging mode:

[0060] It is mainly used for the condition of high-speed driving and large-power driving (acceleration or climbing, etc.), when the vehicle power consumption is greater than a preset threshold, at this time, the range extender and the power battery jointly drive, and the range extender works at high power, and the battery discharges at low power, so as to meet the power demand of the vehicle driving.

[0061] If the enhanced mode is not entered, the target power of the battery in the current mode is obtained according to the vehicle power consumption and the size of the battery SOC in combination with the battery characteristic parameters, and the target power of the range extender is calculated as follows:

[0062] Range extender target power = vehicle power consumption - battery target power in discharge mode

[0063] After the target power of the range extender is calculated, the output power of the range extender is obtained according to the selected several high-efficiency power points of the range extender by using the nearest neighbor principle.

[0064] When the slope is greater than a preset threshold, or the battery SOC is less than a preset threshold, or the vehicle speed is greater than a preset threshold, the system directly enters the enhanced mode, at this time the range extender alternately works at the highest power point and the second highest power point for a certain period of time, under the premise of ensuring the reliability of the range extender, the power generation power of the range extender is as high as possible to meet the subsequent possible high-power demand working condition and reserve power in advance. When the slope is less than a preset threshold, the battery SOC is greater than a preset threshold, and the vehicle speed is less than a preset threshold, the enhanced mode is exited.

[0065] When the vehicle power consumption is less than a preset threshold, the system enters the starting mode; otherwise, the discharge mode is maintained.

[0066] Electricity maintenance mode:

[0067] It is mainly used for urban low-speed driving conditions to maintain the battery SOC in a certain interval to keep the battery power balance. At this time, the range extender meets the driving while charging the power battery.

[0068] When the vehicle power consumption is greater than a preset threshold, the discharge mode is entered; otherwise, the target power of the battery in the electricity maintenance mode is obtained according to the battery pack temperature and the size of the battery SOC in combination with the battery characteristic parameters, and the target power of the range extender is calculated as follows:

[0069] Range extender target power = vehicle power consumption - battery target power in electricity maintenance mode

[0070] After the target power of the range extender is calculated, the output power of the range extender is obtained according to the selected several high-efficiency power points of the range extender by using the nearest neighbor principle.

[0071] When the battery SOC is greater than a preset threshold, the system enters the starting mode, otherwise, the electricity maintenance mode is maintained.

[0072] Range extender reverse drag mode:

[0073] As shown in FIG. 3, when the vehicle brakes on a long downhill slope, forced energy recovery function can be realized by charging the battery, but due to the limitation of the charging power of the battery itself, the effect of motor reverse drag braking is not good. In addition to charging the battery, the application also considers opening the reverse drag mode of the range extender as an energy consumption unit to enhance the braking effect of the whole vehicle.

[0074] The working method of the range extender as an energy consumption unit is that the range extender adds an auxiliary braking unit, i.e. exhaust brake and in-cylinder brake of the engine. When the range extender needs to consume energy, the motor runs at a certain speed by speed control, and the engine opens the auxiliary brake (exhaust brake and in-cylinder brake). At this time, the engine is an energy consumption unit, and the change of energy consumption power of the range extender can be realized by controlling the motor speed. The higher the motor speed, the greater the energy consumption power of the range extender.

[0075] When the driver steps on the brake or the vehicle hill descent function is turned on, reverse drag braking is needed. The range extender is switched from the power generation mode to the reverse drag mode, and the range extender consumes energy as the load of the whole vehicle. At this time, the maximum limit of forced energy recovery power = the long-term maximum charging power of the battery + the maximum power consumption of the range extender.

[0076] When the system detects that the driver steps on the brake, the energy recovery power is obtained according to the opening degree of the brake pedal. Whether the range extender works as a load for reverse drag braking is judged according to the size of the energy recovery power and the maximum charging power of the battery. When the energy recovery power is greater than the maximum charging power of the battery, the range extender opens the reverse drag mode, and the range extender works at a certain power consumption. At this time, the power consumption of the range extender = energy recovery power - maximum charging power of the battery.

[0077] This mode combines battery charging and range extender reverse drag for energy recovery, breaks the limitation of the original battery charging power, improves the energy recovery effect, improves the convenience of driver operation, reduces the wear of brake pads, optimizes the braking effect of the vehicle, increases the cruising range of the new energy crane, and improves the fuel economy.

Claims

1. A power control method of a range-extender hybrid system, characterized in that: the range-extender hybrid system comprises a system starting mode, a discharging mode, an electric quantity maintaining mode and a range-extender reverse drag mode; after the whole vehicle is powered on, it is by default entered into the system starting mode, at this time the range-extender is in a closed state and is only driven by a power battery; it is judged whether the whole vehicle power consumption is greater than or equal to an upper limit of a preset threshold value: if yes, the discharging mode is entered, the range-extender is turned on, at this time the range-extender works at high power and the battery discharges at low power, the power demand of the whole vehicle running is met, when the whole vehicle power consumption is less than a lower limit of the preset threshold value, the discharging mode is exited; if no, it is judged whether the battery SOC is less than the lower limit of the preset threshold value, if yes, the electric quantity maintaining mode is switched to, at this time the range-extender meets the vehicle running power and the demand power of the battery charging is mainly used to maintain the battery SOC in a certain electric quantity interval, when the battery SOC is greater than the upper limit of the preset threshold value, the electric quantity maintaining mode is exited and the system starting mode is kept; when the vehicle hill slow descending function or the like is started and needs to be reverse dragged, the range-extender is switched from the power generation mode to the reverse drag mode, the range-extender is consumed as the whole vehicle load, at this time the maximum limit of the forced energy recovery power = the long-term maximum charging power of the battery + the maximum power consumption of the range-extender; when the system detects that the driver steps on the brake, the energy recovery power is obtained according to the opening degree of the brake pedal, whether the range-extender works as the load for the reverse drag braking is judged according to the energy recovery power and the maximum charging power of the battery, when the energy recovery power is greater than the maximum charging power of the battery, the range-extender starts the reverse drag mode and works at a certain power consumption, at this time the power consumption of the range-extender = the energy recovery power - the maximum charging power of the battery.

2. The power control method of the range extended hybrid system according to claim 1, wherein, In the discharging mode, in addition to the range-extender working at several high-efficiency power points, an enhanced mode is additionally set: in the discharging mode, the power is counted according to the vehicle running condition, the highest power point of the range-extender is selected as the highest power point of the engine, the highest power point of the range-extender which can be long-time operated in the normal mode is selected as the second highest power point of the range-extender, when the slope is greater than a preset threshold value or the battery SOC is less than a preset threshold value or the vehicle speed is greater than a preset threshold value, the system directly enters the enhanced mode, at this time the range-extender alternately works at the highest power point and the second highest power point for a period of time, when the slope is less than the preset threshold value, the battery SOC is greater than the preset threshold value and the vehicle speed is less than the preset threshold value, the enhanced mode is exited.

3. The power control method of the range-extender hybrid system according to claim 2, characterized in that: in the discharging mode, if the enhanced mode is not entered, the target power of the battery in the current mode is obtained according to the whole vehicle power consumption and the size of the battery SOC in combination with the battery characteristic parameters, the target power of the range-extender is calculated as follows: range-extender target power = whole vehicle power consumption - battery target power in discharging mode after the target power of the range-extender is calculated, the output power of the range-extender is obtained according to the selected several high-efficiency power points of the range-extender by using the nearest neighbor principle; when the whole vehicle power consumption is less than the preset threshold value, the system starting mode is entered; otherwise, the discharging mode is maintained.

4. The power control method of the extended-range hybrid system according to claim 2, characterized in that: In the electric quantity maintaining mode, when the vehicle power consumption is greater than a preset threshold, the discharge mode is entered; otherwise, in combination with the battery characteristic parameters, the battery target power in the electric quantity maintaining mode is obtained according to the battery pack temperature and the battery SOC, and the calculation of the extender target power is as follows: Extender target power = vehicle power consumption - battery target power in the electric quantity maintaining mode After the target power of the extender is calculated, the output power of the extender is obtained according to the selected several high-efficiency power points of the extender by using the nearest neighbor principle. When the battery SOC is greater than a preset threshold, the system starting mode is entered, otherwise, the electric quantity maintaining mode is maintained.

5. A range extended hybrid system, characterized by: The extended-range hybrid system comprises an extender composed of an engine and a generator, a power battery, a multi-in-one controller connected with the extender and the power battery, an electric motor connected with the multi-in-one controller, a transmission system connected with the electric motor, and wheels, and is operated to realize the power control method of claim 1.

6. A crane using the extended-range hybrid system of claim 5.

Images